Generic `JsResult<R>` in `context.throw_` methods (#1734)

Previously when we had the `context.throw_` methods (like `context.thtrow_type_error()`) they were limited as to where we could call them, e.i. a function that returned `JsResult<JsValue>`. So we had to call the `context.construct_` methods with an explicit `Err()` enum wrap to throw in functions that returned non-jsvalues (which happens a lot).
Now, with this PR the throw methods have a generic `JsResult<R>` return that can return in any `JsResult<T>` returning function. Which cleans the API and makes the user experience a bit better.

```rust
return Err(context.construct_type_error("..."));
// to
return context.throw_type_error("...");
```

boa/src/bigint.rs

@@ -166,7 +166,7 @@ impl JsBigInt {
         let y = if let Some(y) = y.inner.to_biguint() {
             y
         } else {
-            return Err(context.construct_range_error("BigInt negative exponent"));
+            return context.throw_range_error("BigInt negative exponent");
         };
 
         let num_bits = (x.inner.bits() as f64
@@ -175,7 +175,7 @@ impl JsBigInt {
             + 1f64;
 
         if num_bits > 1_000_000_000f64 {
-            return Err(context.construct_range_error("Maximum BigInt size exceeded"));
+            return context.throw_range_error("Maximum BigInt size exceeded");
         }
 
         Ok(Self::new(x.inner.as_ref().clone().pow(y)))
@@ -192,7 +192,7 @@ impl JsBigInt {
 
             Ok(Self::new(inner))
         } else {
-            Err(context.construct_range_error("Maximum BigInt size exceeded"))
+            context.throw_range_error("Maximum BigInt size exceeded")
         }
     }
 
@@ -207,7 +207,7 @@ impl JsBigInt {
 
             Ok(Self::new(inner))
         } else {
-            Err(context.construct_range_error("Maximum BigInt size exceeded"))
+            context.throw_range_error("Maximum BigInt size exceeded")
         }
     }
 

boa/src/builtins/array/mod.rs

@@ -165,7 +165,7 @@ impl Array {
                 let int_len = len.to_u32(context).unwrap();
                 // ii. If SameValueZero(intLen, len) is false, throw a RangeError exception.
                 if !JsValue::same_value_zero(&int_len.into(), len) {
-                    return Err(context.construct_range_error("invalid array length"));
+                    return context.throw_range_error("invalid array length");
                 }
                 int_len
             };
@@ -210,7 +210,7 @@ impl Array {
     ) -> JsResult<JsObject> {
         // 1. If length > 2^32 - 1, throw a RangeError exception.
         if length > 2usize.pow(32) - 1 {
-            return Err(context.construct_range_error("array exceeded max size"));
+            return context.throw_range_error("array exceeded max size");
         }
         // 7. Return A.
         // 2. If proto is not present, set proto to %Array.prototype%.
@@ -365,7 +365,7 @@ impl Array {
                     .unwrap(),
             )
         } else {
-            Err(context.construct_type_error("Symbol.species must be a constructor"))
+            context.throw_type_error("Symbol.species must be a constructor")
         }
     }
 
@@ -1669,8 +1669,8 @@ impl Array {
                 } else {
                     // 1. If targetIndex >= 2^53 - 1, throw a TypeError exception
                     if target_index >= Number::MAX_SAFE_INTEGER as u64 {
-                        return Err(context
+                        return context
-                            .construct_type_error("Target index exceeded max safe integer value"));
+                            .throw_type_error("Target index exceeded max safe integer value");
                     }
 
                     // 2. Perform ? CreateDataPropertyOrThrow(target, targetIndex, element)

boa/src/builtins/array_buffer/mod.rs

@@ -363,7 +363,7 @@ impl ArrayBuffer {
         let src_block = if let Some(b) = &self.array_buffer_data {
             b
         } else {
-            return Err(context.construct_syntax_error("Cannot clone detached array buffer"));
+            return context.throw_syntax_error("Cannot clone detached array buffer");
         };
 
         {

boa/src/builtins/intl/mod.rs

@@ -93,9 +93,7 @@ impl Intl {
                 let k_value = o.get(k, context)?;
                 // ii. If Type(kValue) is not String or Object, throw a TypeError exception.
                 if !(k_value.is_object() || k_value.is_string()) {
-                    return Err(context
+                    return context.throw_type_error("locale should be a String or Object");
-                        .throw_type_error("locale should be a String or Object")
-                        .unwrap_err());
                 }
                 // iii. If Type(kValue) is Object and kValue has an [[InitializedLocale]] internal slot, then
                 // TODO: handle checks for InitializedLocale internal slot (there should be an if statement here)

boa/src/builtins/iterable/mod.rs

@@ -149,7 +149,7 @@ impl JsValue {
 
         // 4. If Type(iterator) is not Object, throw a TypeError exception.
         if !iterator.is_object() {
-            return Err(context.construct_type_error("the iterator is not an object"));
+            return context.throw_type_error("the iterator is not an object");
         }
 
         // 5. Let nextMethod be ? GetV(iterator, "next").

boa/src/builtins/json/mod.rs

@@ -448,7 +448,7 @@ impl Json {
 
         // 10. If Type(value) is BigInt, throw a TypeError exception.
         if value.is_bigint() {
-            return Err(context.construct_type_error("cannot serialize bigint to JSON"));
+            return context.throw_type_error("cannot serialize bigint to JSON");
         }
 
         // 11. If Type(value) is Object and IsCallable(value) is false, then
@@ -531,7 +531,7 @@ impl Json {
         // 1. If state.[[Stack]] contains value, throw a TypeError exception because the structure is cyclical.
         let limiter = RecursionLimiter::new(value);
         if limiter.live {
-            return Err(context.construct_type_error("cyclic object value"));
+            return context.throw_type_error("cyclic object value");
         }
 
         // 2. Append value to state.[[Stack]].
@@ -644,7 +644,7 @@ impl Json {
         // 1. If state.[[Stack]] contains value, throw a TypeError exception because the structure is cyclical.
         let limiter = RecursionLimiter::new(value);
         if limiter.live {
-            return Err(context.construct_type_error("cyclic object value"));
+            return context.throw_type_error("cyclic object value");
         }
 
         // 2. Append value to state.[[Stack]].

boa/src/builtins/number/mod.rs

@@ -222,8 +222,8 @@ impl Number {
         let this_str_num = if let Some(precision) = precision {
             // 5. If f < 0 or f > 100, throw a RangeError exception.
             if !(0..=100).contains(&precision) {
-                return Err(context
+                return context
-                    .construct_range_error("toExponential() argument must be between 0 and 100"));
+                    .throw_range_error("toExponential() argument must be between 0 and 100");
             }
             f64_to_exponential_with_precision(this_num, precision as usize)
         } else {
@@ -256,9 +256,8 @@ impl Number {
                 0..=100 => n.to_integer(context)? as usize,
                 // 4, 5. If f < 0 or f > 100, throw a RangeError exception.
                 _ => {
-                    return Err(context.construct_range_error(
+                    return context
-                        "toFixed() digits argument must be between 0 and 100",
+                        .throw_range_error("toFixed() digits argument must be between 0 and 100")
-                    ))
                 }
             },
             // 3. If fractionDigits is undefined, then f is 0.

boa/src/builtins/regexp/mod.rs

@@ -332,8 +332,8 @@ impl RegExp {
         // 14. Set obj.[[RegExpMatcher]] to the Abstract Closure that evaluates parseResult by applying the semantics provided in 22.2.2 using patternCharacters as the pattern's List of SourceCharacter values and F as the flag parameters.
         let matcher = match Regex::with_flags(&p, f.as_ref()) {
             Err(error) => {
-                return Err(context
+                return context
-                    .construct_syntax_error(format!("failed to create matcher: {}", error.text)));
+                    .throw_syntax_error(format!("failed to create matcher: {}", error.text));
             }
             Ok(val) => val,
         };
@@ -779,9 +779,7 @@ impl RegExp {
 
             // b. If Type(result) is neither Object nor Null, throw a TypeError exception.
             if !result.is_object() && !result.is_null() {
-                return Err(
+                return context.throw_type_error("regexp exec returned neither object nor null");
-                    context.construct_type_error("regexp exec returned neither object nor null")
-                );
             }
 
             // c. Return result.
@@ -790,7 +788,7 @@ impl RegExp {
 
         // 5. Perform ? RequireInternalSlot(R, [[RegExpMatcher]]).
         if !this.is_regexp() {
-            return Err(context.construct_type_error("RegExpExec called with invalid value"));
+            return context.throw_type_error("RegExpExec called with invalid value");
         }
 
         // 6. Return ? RegExpBuiltinExec(R, S).
@@ -814,9 +812,7 @@ impl RegExp {
             if let Some(rx) = obj.as_regexp() {
                 rx.clone()
             } else {
-                return Err(
+                return context.throw_type_error("RegExpBuiltinExec called with invalid value");
-                    context.construct_type_error("RegExpBuiltinExec called with invalid value")
-                );
             }
         };
 
@@ -870,9 +866,8 @@ impl RegExp {
             ) {
                 Ok(s) => s.len(),
                 Err(_) => {
-                    return Err(context.construct_type_error(
+                    return context
-                        "Failed to get byte index from utf16 encoded string",
+                        .throw_type_error("Failed to get byte index from utf16 encoded string")
-                    ))
                 }
             };
             let r = matcher.find_from(&input, last_byte_index).next();
@@ -1046,9 +1041,8 @@ impl RegExp {
         let rx = if let Some(rx) = this.as_object() {
             rx
         } else {
-            return Err(context.construct_type_error(
+            return context
-                "RegExp.prototype.match method called on incompatible value",
+                .throw_type_error("RegExp.prototype.match method called on incompatible value");
-            ));
         };
 
         // 3. Let S be ? ToString(string).
@@ -1495,9 +1489,9 @@ impl RegExp {
         let rx = if let Some(rx) = this.as_object() {
             rx
         } else {
-            return Err(context.construct_type_error(
+            return context.throw_type_error(
                 "RegExp.prototype[Symbol.search] method called on incompatible value",
-            ));
+            );
         };
 
         // 3. Let S be ? ToString(string).
@@ -1557,9 +1551,8 @@ impl RegExp {
         let rx = if let Some(rx) = this.as_object() {
             rx
         } else {
-            return Err(context.construct_type_error(
+            return context
-                "RegExp.prototype.split method called on incompatible value",
+                .throw_type_error("RegExp.prototype.split method called on incompatible value");
-            ));
         };
 
         // 3. Let S be ? ToString(string).

boa/src/builtins/typed_array/mod.rs

@@ -547,7 +547,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -682,7 +682,7 @@ impl TypedArray {
 
             // 2. Perform ? ValidateTypedArray(O).
             if o.is_detached() {
-                return Err(context.construct_type_error("Buffer of the typed array is detached"));
+                return context.throw_type_error("Buffer of the typed array is detached");
             }
 
             // 3. Let len be O.[[ArrayLength]].
@@ -747,7 +747,7 @@ impl TypedArray {
             // b. Let buffer be O.[[ViewedArrayBuffer]].
             // c. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
             if o.is_detached() {
-                return Err(context.construct_type_error("Buffer of the typed array is detached"));
+                return context.throw_type_error("Buffer of the typed array is detached");
             }
 
             // d. Let typedArrayName be the String value of O.[[TypedArrayName]].
@@ -848,7 +848,7 @@ impl TypedArray {
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?
             .is_detached()
         {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Return CreateArrayIterator(O, key+value).
@@ -876,7 +876,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -935,7 +935,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -980,7 +980,7 @@ impl TypedArray {
 
         // 14. If IsDetachedBuffer(O.[[ViewedArrayBuffer]]) is true, throw a TypeError exception.
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 15. Repeat, while k < final,
@@ -1015,7 +1015,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1096,7 +1096,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1154,7 +1154,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1211,7 +1211,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1263,7 +1263,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1336,7 +1336,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1418,7 +1418,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1475,7 +1475,7 @@ impl TypedArray {
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?
             .is_detached()
         {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Return CreateArrayIterator(O, key).
@@ -1503,7 +1503,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1606,7 +1606,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1664,7 +1664,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1741,7 +1741,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1821,7 +1821,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -1933,7 +1933,7 @@ impl TypedArray {
         // 1. Let targetBuffer be target.[[ViewedArrayBuffer]].
         // 2. If IsDetachedBuffer(targetBuffer) is true, throw a TypeError exception.
         if target_array.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
         let target_buffer_obj = target_array
             .viewed_array_buffer()
@@ -1945,7 +1945,7 @@ impl TypedArray {
         // 4. Let srcBuffer be source.[[ViewedArrayBuffer]].
         // 5. If IsDetachedBuffer(srcBuffer) is true, throw a TypeError exception.
         if source_array.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
         let mut src_buffer_obj = source_array
             .viewed_array_buffer()
@@ -1979,23 +1979,23 @@ impl TypedArray {
         let target_offset = match target_offset {
             IntegerOrInfinity::Integer(i) if i >= 0 => i as usize,
             IntegerOrInfinity::PositiveInfinity => {
-                return Err(context.construct_range_error("Target offset cannot be Infinity"))
+                return context.throw_range_error("Target offset cannot be Infinity");
             }
             _ => unreachable!(),
         };
 
         // 16. If srcLength + targetOffset > targetLength, throw a RangeError exception.
         if src_length + target_offset > target_length {
-            return Err(context.construct_range_error(
+            return context.throw_range_error(
                 "Source typed array and target offset longer than target typed array",
-            ));
+            );
         }
 
         // 17. If target.[[ContentType]] ≠ source.[[ContentType]], throw a TypeError exception.
         if target_name.content_type() != src_name.content_type() {
-            return Err(context.construct_type_error(
+            return context.throw_type_error(
                 "Source typed array and target typed array have different content types",
-            ));
+            );
         }
 
         // TODO: Shared Array Buffer
@@ -2142,7 +2142,7 @@ impl TypedArray {
         // 1. Let targetBuffer be target.[[ViewedArrayBuffer]].
         // 2. If IsDetachedBuffer(targetBuffer) is true, throw a TypeError exception.
         if target_array.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let targetLength be target.[[ArrayLength]].
@@ -2167,7 +2167,7 @@ impl TypedArray {
         let target_offset = match target_offset {
             // 10. If targetOffset is +∞, throw a RangeError exception.
             IntegerOrInfinity::PositiveInfinity => {
-                return Err(context.construct_range_error("Target offset cannot be Infinity"))
+                return context.throw_range_error("Target offset cannot be Infinity")
             }
             IntegerOrInfinity::Integer(i) if i >= 0 => i as usize,
             _ => unreachable!(),
@@ -2175,9 +2175,9 @@ impl TypedArray {
 
         // 11. If srcLength + targetOffset > targetLength, throw a RangeError exception.
         if src_length + target_offset > target_length {
-            return Err(context.construct_range_error(
+            return context.throw_range_error(
                 "Source object and target offset longer than target typed array",
-            ));
+            );
         }
 
         // 12. Let targetByteIndex be targetOffset × targetElementSize + targetByteOffset.
@@ -2213,9 +2213,7 @@ impl TypedArray {
 
             // e. If IsDetachedBuffer(targetBuffer) is true, throw a TypeError exception.
             if target_buffer.is_detached_buffer() {
-                return Err(
+                return context.throw_type_error("Cannot set value on detached array buffer");
-                    context.construct_type_error("Cannot set value on detached array buffer")
-                );
             }
 
             // f. Perform SetValueInBuffer(targetBuffer, targetByteIndex, targetType, value, true, Unordered).
@@ -2255,7 +2253,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -2304,7 +2302,7 @@ impl TypedArray {
         if count > 0 {
             // a. If IsDetachedBuffer(O.[[ViewedArrayBuffer]]) is true, throw a TypeError exception.
             if o.is_detached() {
-                return Err(context.construct_type_error("Buffer of the typed array is detached"));
+                return context.throw_type_error("Buffer of the typed array is detached");
             }
 
             // b. Let srcName be the String value of O.[[TypedArrayName]].
@@ -2419,7 +2417,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Let len be O.[[ArrayLength]].
@@ -2545,8 +2543,8 @@ impl TypedArray {
                     .expect("Must be array buffer")
                     .is_detached_buffer()
                 {
-                    return Err(context
+                    return context
-                        .construct_type_error("Cannot sort typed array with detached buffer"));
+                        .throw_type_error("Cannot sort typed array with detached buffer");
                 }
 
                 // c. If v is NaN, return +0𝔽.
@@ -2770,7 +2768,7 @@ impl TypedArray {
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?
             .is_detached()
         {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. Return CreateArrayIterator(O, value).
@@ -2848,8 +2846,8 @@ impl TypedArray {
             .content_type()
             != typed_array_name.content_type()
         {
-            return Err(context
+            return context
-                .construct_type_error("New typed array has different context type than exemplar"));
+                .throw_type_error("New typed array has different context type than exemplar");
         }
 
         // 6. Return result.
@@ -2879,7 +2877,7 @@ impl TypedArray {
             .as_typed_array()
             .ok_or_else(|| context.construct_type_error("Value is not a typed array object"))?;
         if o.is_detached() {
-            return Err(context.construct_type_error("Buffer of the typed array is detached"));
+            return context.throw_type_error("Buffer of the typed array is detached");
         }
 
         // 3. If argumentList is a List of a single Number, then
@@ -2887,8 +2885,8 @@ impl TypedArray {
             if let Some(number) = args[0].as_number() {
                 // a. If newTypedArray.[[ArrayLength]] < ℝ(argumentList[0]), throw a TypeError exception.
                 if (o.array_length() as f64) < number {
-                    return Err(context
+                    return context
-                        .construct_type_error("New typed array length is smaller than expected"));
+                        .throw_type_error("New typed array length is smaller than expected");
                 }
             }
         }
@@ -3035,9 +3033,7 @@ impl TypedArray {
         // 1. Let srcData be srcArray.[[ViewedArrayBuffer]].
         // 2. If IsDetachedBuffer(srcData) is true, throw a TypeError exception.
         if src_array.is_detached() {
-            return Err(
+            return context.throw_type_error("Cannot initialize typed array from detached buffer");
-                context.construct_type_error("Cannot initialize typed array from detached buffer")
-            );
         }
         let src_data_obj = src_array
             .viewed_array_buffer()
@@ -3095,15 +3091,14 @@ impl TypedArray {
 
             // b. If IsDetachedBuffer(srcData) is true, throw a TypeError exception.
             if src_data.is_detached_buffer() {
-                return Err(context
+                return context
-                    .construct_type_error("Cannot initialize typed array from detached buffer"));
+                    .throw_type_error("Cannot initialize typed array from detached buffer");
             }
 
             // c. If srcArray.[[ContentType]] ≠ O.[[ContentType]], throw a TypeError exception.
             if src_name.content_type() != constructor_name.content_type() {
-                return Err(context.construct_type_error(
+                return context
-                    "Cannot initialize typed array from different content type",
+                    .throw_type_error("Cannot initialize typed array from different content type");
-                ));
             }
 
             // d. Let srcByteIndex be srcByteOffset.
@@ -3188,7 +3183,7 @@ impl TypedArray {
 
         // 4. If offset modulo elementSize ≠ 0, throw a RangeError exception.
         if offset % constructor_name.element_size() != 0 {
-            return Err(context.construct_range_error("Invalid length for typed array"));
+            return context.throw_range_error("Invalid length for typed array");
         }
 
         let buffer_byte_length = {
@@ -3199,8 +3194,8 @@ impl TypedArray {
 
             // 6. If IsDetachedBuffer(buffer) is true, throw a TypeError exception.
             if buffer_array.is_detached_buffer() {
-                return Err(context
+                return context
-                    .construct_type_error("Cannot construct typed array from detached buffer"));
+                    .throw_type_error("Cannot construct typed array from detached buffer");
             }
 
             // 7. Let bufferByteLength be buffer.[[ArrayBufferByteLength]].
@@ -3211,7 +3206,7 @@ impl TypedArray {
         let new_byte_length = if length.is_undefined() {
             // a. If bufferByteLength modulo elementSize ≠ 0, throw a RangeError exception.
             if buffer_byte_length % constructor_name.element_size() != 0 {
-                return Err(context.construct_range_error("Invalid length for typed array"));
+                return context.throw_range_error("Invalid length for typed array");
             }
 
             // b. Let newByteLength be bufferByteLength - offset.
@@ -3219,7 +3214,7 @@ impl TypedArray {
 
             // c. If newByteLength < 0, throw a RangeError exception.
             if new_byte_length < 0 {
-                return Err(context.construct_range_error("Invalid length for typed array"));
+                return context.throw_range_error("Invalid length for typed array");
             }
 
             new_byte_length as usize
@@ -3233,7 +3228,7 @@ impl TypedArray {
 
             // b. If offset + newByteLength > bufferByteLength, throw a RangeError exception.
             if offset + new_byte_length > buffer_byte_length {
-                return Err(context.construct_range_error("Invalid length for typed array"));
+                return context.throw_range_error("Invalid length for typed array");
             }
 
             new_byte_length

boa/src/context.rs

@@ -555,7 +555,7 @@ impl Context {
 
     /// Throws a `Error` with the specified message.
     #[inline]
-    pub fn throw_error<M>(&mut self, message: M) -> JsResult<JsValue>
+    pub fn throw_error<M, R>(&mut self, message: M) -> JsResult<R>
     where
         M: Into<Box<str>>,
     {
@@ -582,7 +582,7 @@ impl Context {
 
     /// Throws a `RangeError` with the specified message.
     #[inline]
-    pub fn throw_range_error<M>(&mut self, message: M) -> JsResult<JsValue>
+    pub fn throw_range_error<M, R>(&mut self, message: M) -> JsResult<R>
     where
         M: Into<Box<str>>,
     {
@@ -609,7 +609,7 @@ impl Context {
 
     /// Throws a `TypeError` with the specified message.
     #[inline]
-    pub fn throw_type_error<M>(&mut self, message: M) -> JsResult<JsValue>
+    pub fn throw_type_error<M, R>(&mut self, message: M) -> JsResult<R>
     where
         M: Into<Box<str>>,
     {
@@ -636,7 +636,7 @@ impl Context {
 
     /// Throws a `ReferenceError` with the specified message.
     #[inline]
-    pub fn throw_reference_error<M>(&mut self, message: M) -> JsResult<JsValue>
+    pub fn throw_reference_error<M, R>(&mut self, message: M) -> JsResult<R>
     where
         M: Into<Box<str>>,
     {
@@ -663,7 +663,7 @@ impl Context {
 
     /// Throws a `SyntaxError` with the specified message.
     #[inline]
-    pub fn throw_syntax_error<M>(&mut self, message: M) -> JsResult<JsValue>
+    pub fn throw_syntax_error<M, R>(&mut self, message: M) -> JsResult<R>
     where
         M: Into<Box<str>>,
     {
@@ -705,7 +705,7 @@ impl Context {
     }
 
     /// Throws a `EvalError` with the specified message.
-    pub fn throw_eval_error<M>(&mut self, message: M) -> JsResult<JsValue>
+    pub fn throw_eval_error<M, R>(&mut self, message: M) -> JsResult<R>
     where
         M: Into<Box<str>>,
     {

boa/src/environment/declarative_environment_record.rs

@@ -179,7 +179,7 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         if self.env_rec.borrow().get(name).is_none() {
             // a. If S is true, throw a ReferenceError exception.
             if strict {
-                return Err(context.construct_reference_error(format!("{} not found", name)));
+                return context.throw_reference_error(format!("{} not found", name));
             }
 
             // b. Perform envRec.CreateMutableBinding(N, true).
@@ -204,9 +204,7 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
 
         // 3. If the binding for N in envRec has not yet been initialized, throw a ReferenceError exception.
         if binding_value_is_none {
-            return Err(
+            return context.throw_reference_error(format!("{} has not been initialized", name));
-                context.construct_reference_error(format!("{} has not been initialized", name))
-            );
         // 4. Else if the binding for N in envRec is a mutable binding, change its bound value to V.
         } else if binding_mutable {
             let mut env_rec = self.env_rec.borrow_mut();
@@ -216,8 +214,8 @@ impl EnvironmentRecordTrait for DeclarativeEnvironmentRecord {
         // a. Assert: This is an attempt to change the value of an immutable binding.
         // b. If S is true, throw a TypeError exception.
         } else if strict {
-            return Err(context
+            return context
-                .construct_type_error(format!("Cannot mutate an immutable binding {}", name)));
+                .throw_type_error(format!("Cannot mutate an immutable binding {}", name));
         }
 
         // 6. Return NormalCompletion(empty).

boa/src/environment/global_environment_record.rs

@@ -300,9 +300,7 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         // 1. Let DclRec be envRec.[[DeclarativeRecord]].
         // 2. If DclRec.HasBinding(N) is true, throw a TypeError exception.
         if !allow_name_reuse && self.declarative_record.has_binding(name, context)? {
-            return Err(
+            return context.throw_type_error(format!("Binding already exists for {}", name));
-                context.construct_type_error(format!("Binding already exists for {}", name))
-            );
         }
 
         // 3. Return DclRec.CreateMutableBinding(N, D).
@@ -325,9 +323,7 @@ impl EnvironmentRecordTrait for GlobalEnvironmentRecord {
         // 1. Let DclRec be envRec.[[DeclarativeRecord]].
         // 2. If DclRec.HasBinding(N) is true, throw a TypeError exception.
         if self.declarative_record.has_binding(name, context)? {
-            return Err(
+            return context.throw_type_error(format!("Binding already exists for {}", name));
-                context.construct_type_error(format!("Binding already exists for {}", name))
-            );
         }
 
         // 3. Return DclRec.CreateImmutableBinding(N, S).

boa/src/environment/object_environment_record.rs

@@ -157,7 +157,7 @@ impl EnvironmentRecordTrait for ObjectEnvironmentRecord {
 
         // 3. If stillExists is false and S is true, throw a ReferenceError exception.
         if !still_exists && strict {
-            return Err(context.construct_reference_error("Binding already exists"));
+            return context.throw_reference_error("Binding already exists");
         }
 
         // 4. Return ? Set(bindingObject, N, V, S).

boa/src/lib.rs

@@ -108,10 +108,7 @@ pub(crate) fn forward<T: AsRef<[u8]>>(context: &mut Context, src: T) -> String {
         Err(e) => {
             return format!(
                 "Uncaught {}",
-                context
+                context.construct_syntax_error(e.to_string()).display()
-                    .throw_syntax_error(e.to_string())
-                    .expect_err("interpreter.throw_syntax_error() did not return an error")
-                    .display()
             );
         }
     };
@@ -133,11 +130,7 @@ pub(crate) fn forward_val<T: AsRef<[u8]>>(context: &mut Context, src: T) -> JsRe
     let src_bytes: &[u8] = src.as_ref();
     // Setup executor
     let result = parse(src_bytes, false)
-        .map_err(|e| {
+        .map_err(|e| context.construct_syntax_error(e.to_string()))
-            context
-                .throw_syntax_error(e.to_string())
-                .expect_err("interpreter.throw_syntax_error() did not return an error")
-        })
         .and_then(|expr| expr.run(context));
 
     // The main_timer needs to be dropped before the BoaProfiler is.

boa/src/object/internal_methods/array.rs

@@ -62,7 +62,7 @@ pub(crate) fn array_exotic_define_own_property(
             // 5. If SameValueZero(newLen, numberLen) is false, throw a RangeError exception.
             #[allow(clippy::float_cmp)]
             if new_len as f64 != number_len {
-                return Err(context.construct_range_error("bad length for array"));
+                return context.throw_range_error("bad length for array");
             }
 
             // 2. Let newLenDesc be a copy of Desc.

boa/src/object/internal_methods/proxy.rs

@@ -100,9 +100,7 @@ pub(crate) fn proxy_exotic_get_prototype_of(
     let handler_proto = match &handler_proto {
         JsValue::Object(obj) => Some(obj.clone()),
         JsValue::Null => None,
-        _ => {
+        _ => return context.throw_type_error("Proxy trap result is neither object nor null"),
-            return Err(context.construct_type_error("Proxy trap result is neither object nor null"))
-        }
     };
 
     // 9. Let extensibleTarget be ? IsExtensible(target).
@@ -116,7 +114,7 @@ pub(crate) fn proxy_exotic_get_prototype_of(
 
     // 12. If SameValue(handlerProto, targetProto) is false, throw a TypeError exception.
     if handler_proto != target_proto {
-        return Err(context.construct_type_error("Proxy trap returned unexpected prototype"));
+        return context.throw_type_error("Proxy trap returned unexpected prototype");
     }
 
     // 13. Return handlerProto.
@@ -181,7 +179,7 @@ pub(crate) fn proxy_exotic_set_prototype_of(
 
     // 12. If SameValue(V, targetProto) is false, throw a TypeError exception.
     if val != target_proto {
-        return Err(context.construct_type_error("Proxy trap failed to set prototype"));
+        return context.throw_type_error("Proxy trap failed to set prototype");
     }
 
     // 13. Return true.
@@ -225,7 +223,7 @@ pub(crate) fn proxy_exotic_is_extensible(obj: &JsObject, context: &mut Context)
 
     // 9. If SameValue(booleanTrapResult, targetResult) is false, throw a TypeError exception.
     if boolean_trap_result != target_result {
-        return Err(context.construct_type_error("Proxy trap returned unexpected extensible value"));
+        return context.throw_type_error("Proxy trap returned unexpected extensible value");
     }
 
     // 10. Return booleanTrapResult.
@@ -271,7 +269,7 @@ pub(crate) fn proxy_exotic_prevent_extensions(
     if boolean_trap_result && target.is_extensible(context)? {
         // a. Let extensibleTarget be ? IsExtensible(target).
         // b. If extensibleTarget is true, throw a TypeError exception.
-        return Err(context.construct_type_error("Proxy trap failed to set extensible"));
+        return context.throw_type_error("Proxy trap failed to set extensible");
     }
 
     // 9. Return booleanTrapResult.
@@ -318,9 +316,7 @@ pub(crate) fn proxy_exotic_get_own_property(
 
     // 8. If Type(trapResultObj) is neither Object nor Undefined, throw a TypeError exception.
     if !trap_result_obj.is_object() && !trap_result_obj.is_undefined() {
-        return Err(
+        return context.throw_type_error("Proxy trap result is neither object nor undefined");
-            context.construct_type_error("Proxy trap result is neither object nor undefined")
-        );
     }
 
     // 9. Let targetDesc be ? target.[[GetOwnProperty]](P).
@@ -331,17 +327,17 @@ pub(crate) fn proxy_exotic_get_own_property(
         if let Some(desc) = target_desc {
             // b. If targetDesc.[[Configurable]] is false, throw a TypeError exception.
             if !desc.expect_configurable() {
-                return Err(context.construct_type_error(
+                return context.throw_type_error(
                     "Proxy trap result is undefined adn target result is not configurable",
-                ));
+                );
             }
 
             // c. Let extensibleTarget be ? IsExtensible(target).
             // d. If extensibleTarget is false, throw a TypeError exception.
             if !target.is_extensible(context)? {
-                return Err(context.construct_type_error(
+                return context.throw_type_error(
                     "Proxy trap result is undefined and target is not extensible",
-                ));
+                );
             // e. Return undefined.
             } else {
                 return Ok(None);
@@ -368,7 +364,7 @@ pub(crate) fn proxy_exotic_get_own_property(
         result_desc.clone(),
         target_desc.clone(),
     ) {
-        return Err(context.construct_type_error("Proxy trap returned unexpected property"));
+        return context.throw_type_error("Proxy trap returned unexpected property");
     }
 
     // 16. If resultDesc.[[Configurable]] is false, then
@@ -380,17 +376,17 @@ pub(crate) fn proxy_exotic_get_own_property(
                 if let Some(false) = result_desc.writable() {
                     // i. If targetDesc.[[Writable]] is true, throw a TypeError exception.
                     if desc.expect_writable() {
-                        return Err(
+                        return
-                            context.construct_type_error("Proxy trap result is writable and not configurable while target result is not configurable")
+                            context.throw_type_error("Proxy trap result is writable and not configurable while target result is not configurable")
-                        );
+                        ;
                     }
                 }
             }
             // i. Throw a TypeError exception.
             _ => {
-                return Err(context.construct_type_error(
+                return context.throw_type_error(
                     "Proxy trap result is not configurable and target result is undefined",
-                ))
+                )
             }
         }
     }
@@ -461,12 +457,12 @@ pub(crate) fn proxy_exotic_define_own_property(
         None => {
             // a. If extensibleTarget is false, throw a TypeError exception.
             if !extensible_target {
-                return Err(context.construct_type_error("Proxy trap failed to set property"));
+                return context.throw_type_error("Proxy trap failed to set property");
             }
 
             // b. If settingConfigFalse is true, throw a TypeError exception.
             if setting_config_false {
-                return Err(context.construct_type_error("Proxy trap failed to set property"));
+                return context.throw_type_error("Proxy trap failed to set property");
             }
         }
         // 15. Else,
@@ -477,16 +473,14 @@ pub(crate) fn proxy_exotic_define_own_property(
                 desc.clone(),
                 Some(target_desc.clone()),
             ) {
-                return Err(
+                return context.throw_type_error("Proxy trap set property to unexpected value");
-                    context.construct_type_error("Proxy trap set property to unexpected value")
-                );
             }
 
             // b. If settingConfigFalse is true and targetDesc.[[Configurable]] is true, throw a TypeError exception.
             if setting_config_false && target_desc.expect_configurable() {
-                return Err(context.construct_type_error(
+                return context.throw_type_error(
                     "Proxy trap set property with unexpected configurable field",
-                ));
+                );
             }
 
             // c. If IsDataDescriptor(targetDesc) is true, targetDesc.[[Configurable]] is false, and targetDesc.[[Writable]] is true, then
@@ -497,9 +491,9 @@ pub(crate) fn proxy_exotic_define_own_property(
                 // i. If Desc has a [[Writable]] field and Desc.[[Writable]] is false, throw a TypeError exception.
                 if let Some(writable) = desc.writable() {
                     if !writable {
-                        return Err(context.construct_type_error(
+                        return context.throw_type_error(
                             "Proxy trap set property with unexpected writable field",
-                        ));
+                        );
                     }
                 }
             }
@@ -559,13 +553,13 @@ pub(crate) fn proxy_exotic_has_property(
         if let Some(target_desc) = target_desc {
             // i. If targetDesc.[[Configurable]] is false, throw a TypeError exception.
             if !target_desc.expect_configurable() {
-                return Err(context.construct_type_error("Proxy trap returned unexpected property"));
+                return context.throw_type_error("Proxy trap returned unexpected property");
             }
 
             // ii. Let extensibleTarget be ? IsExtensible(target).
             // iii. If extensibleTarget is false, throw a TypeError exception.
             if !target.is_extensible(context)? {
-                return Err(context.construct_type_error("Proxy trap returned unexpected property"));
+                return context.throw_type_error("Proxy trap returned unexpected property");
             }
         }
     }
@@ -623,8 +617,8 @@ pub(crate) fn proxy_exotic_get(
             if target_desc.is_data_descriptor() && !target_desc.expect_writable() {
                 // i. If SameValue(trapResult, targetDesc.[[Value]]) is false, throw a TypeError exception.
                 if !JsValue::same_value(&trap_result, target_desc.expect_value()) {
-                    return Err(context
+                    return context
-                        .construct_type_error("Proxy trap returned unexpected data descriptor"));
+                        .throw_type_error("Proxy trap returned unexpected data descriptor");
                 }
             }
 
@@ -632,9 +626,8 @@ pub(crate) fn proxy_exotic_get(
             if target_desc.is_accessor_descriptor() && target_desc.expect_get().is_undefined() {
                 // i. If trapResult is not undefined, throw a TypeError exception.
                 if !trap_result.is_undefined() {
-                    return Err(context.construct_type_error(
+                    return context
-                        "Proxy trap returned unexpected accessor descriptor",
+                        .throw_type_error("Proxy trap returned unexpected accessor descriptor");
-                    ));
                 }
             }
         }
@@ -700,9 +693,7 @@ pub(crate) fn proxy_exotic_set(
             if target_desc.is_data_descriptor() && !target_desc.expect_writable() {
                 // i. If SameValue(V, targetDesc.[[Value]]) is false, throw a TypeError exception.
                 if !JsValue::same_value(&value, target_desc.expect_value()) {
-                    return Err(
+                    return context.throw_type_error("Proxy trap set unexpected data descriptor");
-                        context.construct_type_error("Proxy trap set unexpected data descriptor")
-                    );
                 }
             }
 
@@ -711,9 +702,8 @@ pub(crate) fn proxy_exotic_set(
                 // i. If targetDesc.[[Set]] is undefined, throw a TypeError exception.
                 match target_desc.set() {
                     None | Some(&JsValue::Undefined) => {
-                        return Err(context.construct_type_error(
+                        return context
-                            "Proxy trap set unexpected accessor descriptor",
+                            .throw_type_error("Proxy trap set unexpected accessor descriptor");
-                        ));
                     }
                     _ => {}
                 }
@@ -776,7 +766,7 @@ pub(crate) fn proxy_exotic_delete(
         // 11. If targetDesc.[[Configurable]] is false, throw a TypeError exception.
         Some(target_desc) => {
             if !target_desc.expect_configurable() {
-                return Err(context.construct_type_error("Proxy trap failed to delete property"));
+                return context.throw_type_error("Proxy trap failed to delete property");
             }
         }
     }
@@ -784,7 +774,7 @@ pub(crate) fn proxy_exotic_delete(
     // 12. Let extensibleTarget be ? IsExtensible(target).
     // 13. If extensibleTarget is false, throw a TypeError exception.
     if !target.is_extensible(context)? {
-        return Err(context.construct_type_error("Proxy trap failed to delete property"));
+        return context.throw_type_error("Proxy trap failed to delete property");
     }
 
     // 14. Return true.
@@ -835,17 +825,17 @@ pub(crate) fn proxy_exotic_own_property_keys(
         match value {
             JsValue::String(s) => {
                 if !unchecked_result_keys.insert(s.clone().into()) {
-                    return Err(context.construct_type_error(
+                    return context.throw_type_error(
                         "Proxy trap result contains duplicate string property keys",
-                    ));
+                    );
                 }
                 trap_result.push(s.clone().into())
             }
             JsValue::Symbol(s) => {
                 if !unchecked_result_keys.insert(s.clone().into()) {
-                    return Err(context.construct_type_error(
+                    return context.throw_type_error(
                         "Proxy trap result contains duplicate symbol property keys",
-                    ));
+                    );
                 }
                 trap_result.push(s.clone().into())
             }
@@ -895,9 +885,9 @@ pub(crate) fn proxy_exotic_own_property_keys(
         // a. If key is not an element of uncheckedResultKeys, throw a TypeError exception.
         // b. Remove key from uncheckedResultKeys.
         if !unchecked_result_keys.remove(&key) {
-            return Err(context.construct_type_error(
+            return context.throw_type_error(
                 "Proxy trap failed to return all non-configurable property keys",
-            ));
+            );
         }
     }
 
@@ -911,15 +901,14 @@ pub(crate) fn proxy_exotic_own_property_keys(
         // a. If key is not an element of uncheckedResultKeys, throw a TypeError exception.
         // b. Remove key from uncheckedResultKeys.
         if !unchecked_result_keys.remove(&key) {
-            return Err(context.construct_type_error(
+            return context
-                "Proxy trap failed to return all configurable property keys",
+                .throw_type_error("Proxy trap failed to return all configurable property keys");
-            ));
         }
     }
 
     // 22. If uncheckedResultKeys is not empty, throw a TypeError exception.
     if !unchecked_result_keys.is_empty() {
-        return Err(context.construct_type_error("Proxy trap failed to return all property keys"));
+        return context.throw_type_error("Proxy trap failed to return all property keys");
     }
 
     // 23. Return trapResult.
@@ -1014,9 +1003,7 @@ fn proxy_exotic_construct(
 
     // 10. If Type(newObj) is not Object, throw a TypeError exception.
     if !new_obj.is_object() {
-        return Err(
+        return context.throw_type_error("Proxy trap constructor returned non-object value");
-            context.construct_type_error("Proxy trap constructor returned non-object value")
-        );
     }
 
     // 11. Return newObj.

boa/src/object/jsobject.rs

@@ -480,9 +480,7 @@ impl JsObject {
             // b. If IsCallable(getter) is false and getter is not undefined, throw a TypeError exception.
             // todo: extract IsCallable to be callable from Value
             if !getter.is_undefined() && getter.as_object().map_or(true, |o| !o.is_callable()) {
-                return Err(
+                return context.throw_type_error("Property descriptor getter must be callable");
-                    context.construct_type_error("Property descriptor getter must be callable")
-                );
             }
             // c. Set desc.[[Get]] to getter.
             Some(getter)
@@ -498,9 +496,7 @@ impl JsObject {
             // 14.b. If IsCallable(setter) is false and setter is not undefined, throw a TypeError exception.
             // todo: extract IsCallable to be callable from Value
             if !setter.is_undefined() && setter.as_object().map_or(true, |o| !o.is_callable()) {
-                return Err(
+                return context.throw_type_error("Property descriptor setter must be callable");
-                    context.construct_type_error("Property descriptor setter must be callable")
-                );
             }
             // 14.c. Set desc.[[Set]] to setter.
             Some(setter)
@@ -511,10 +507,10 @@ impl JsObject {
         // 15. If desc.[[Get]] is present or desc.[[Set]] is present, then ...
         // a. If desc.[[Value]] is present or desc.[[Writable]] is present, throw a TypeError exception.
         if get.as_ref().or_else(|| set.as_ref()).is_some() && desc.inner().is_data_descriptor() {
-            return Err(context.construct_type_error(
+            return context.throw_type_error(
                 "Invalid property descriptor.\
-            Cannot both specify accessors and a value or writable attribute",
+Cannot both specify accessors and a value or writable attribute",
-            ));
+            );
         }
 
         desc = desc.maybe_get(get).maybe_set(set);

boa/src/object/operations.rs

@@ -91,9 +91,7 @@ impl JsObject {
         let success = self.__set__(key.clone(), value.into(), self.clone().into(), context)?;
         // 5. If success is false and Throw is true, throw a TypeError exception.
         if !success && throw {
-            return Err(
+            return context.throw_type_error(format!("cannot set non-writable property: {}", key));
-                context.construct_type_error(format!("cannot set non-writable property: {}", key))
-            );
         }
         // 6. Return success.
         Ok(success)
@@ -152,7 +150,7 @@ impl JsObject {
         let success = self.create_data_property(key.clone(), value, context)?;
         // 4. If success is false, throw a TypeError exception.
         if !success {
-            return Err(context.construct_type_error(format!("cannot redefine property: {}", key)));
+            return context.throw_type_error(format!("cannot redefine property: {}", key));
         }
         // 5. Return success.
         Ok(success)
@@ -182,7 +180,7 @@ impl JsObject {
         let success = self.__define_own_property__(key.clone(), desc.into(), context)?;
         // 4. If success is false, throw a TypeError exception.
         if !success {
-            return Err(context.construct_type_error(format!("cannot redefine property: {}", key)));
+            return context.throw_type_error(format!("cannot redefine property: {}", key));
         }
         // 5. Return success.
         Ok(success)
@@ -206,7 +204,7 @@ impl JsObject {
         let success = self.__delete__(&key, context)?;
         // 4. If success is false, throw a TypeError exception.
         if !success {
-            return Err(context.construct_type_error(format!("cannot delete property: {}", key)));
+            return context.throw_type_error(format!("cannot delete property: {}", key));
         }
         // 5. Return success.
         Ok(success)
@@ -451,7 +449,7 @@ impl JsObject {
 
         // 4. If Type(C) is not Object, throw a TypeError exception.
         if !c.is_object() {
-            return Err(context.construct_type_error("property 'constructor' is not an object"));
+            return context.throw_type_error("property 'constructor' is not an object");
         }
 
         // 5. Let S be ? Get(C, @@species).
@@ -466,7 +464,7 @@ impl JsObject {
         // 8. Throw a TypeError exception.
         match s.as_object() {
             Some(obj) if obj.is_constructor() => Ok(obj.clone()),
-            _ => Err(context.construct_type_error("property 'constructor' is not a constructor")),
+            _ => context.throw_type_error("property 'constructor' is not a constructor"),
         }
     }
 
@@ -555,8 +553,9 @@ impl JsObject {
             // 5. Return func.
             JsValue::Object(obj) if obj.is_callable() => Ok(Some(obj.clone())),
             // 4. If IsCallable(func) is false, throw a TypeError exception.
-            _ => Err(context
+            _ => {
-                .construct_type_error("value returned for property of object is not a function")),
+                context.throw_type_error("value returned for property of object is not a function")
+            }
         }
     }
 
@@ -667,7 +666,7 @@ impl JsValue {
             let next = obj.get(index, context)?;
             // c. If Type(next) is not an element of elementTypes, throw a TypeError exception.
             if !types.contains(&next.get_type()) {
-                return Err(context.construct_type_error("bad type"));
+                return context.throw_type_error("bad type");
             }
             // d. Append next as the last element of list.
             list.push(next.clone());
@@ -746,8 +745,8 @@ impl JsValue {
             obj
         } else {
             // 5. If Type(P) is not Object, throw a TypeError exception.
-            return Err(context
+            return context
-                .construct_type_error("function has non-object prototype in instanceof check"));
+                .throw_type_error("function has non-object prototype in instanceof check");
         };
 
         // 6. Repeat,

boa/src/syntax/ast/node/declaration/mod.rs

@@ -472,10 +472,10 @@ impl DeclarationPatternObject {
         };
 
         if value.is_null() {
-            return Err(context.construct_type_error("Cannot destructure 'null' value"));
+            return context.throw_type_error("Cannot destructure 'null' value");
         }
         if value.is_undefined() {
-            return Err(context.construct_type_error("Cannot destructure 'undefined' value"));
+            return context.throw_type_error("Cannot destructure 'undefined' value");
         }
 
         // 1. Perform ? RequireObjectCoercible(value).
@@ -685,10 +685,10 @@ impl DeclarationPatternArray {
         };
 
         if value.is_null() {
-            return Err(context.construct_type_error("Cannot destructure 'null' value"));
+            return context.throw_type_error("Cannot destructure 'null' value");
         }
         if value.is_undefined() {
-            return Err(context.construct_type_error("Cannot destructure 'undefined' value"));
+            return context.throw_type_error("Cannot destructure 'undefined' value");
         }
 
         // 1. Let iteratorRecord be ? GetIterator(value).

boa/src/value/mod.rs

@@ -374,7 +374,7 @@ impl JsValue {
             // 5. If success is false and Throw is true, throw a TypeError exception.
             // 6. Return success.
             if !success && throw {
-                return Err(context.construct_type_error("Cannot assign value to property"));
+                return context.throw_type_error("Cannot assign value to property");
             } else {
                 return Ok(value);
             }
@@ -435,7 +435,7 @@ impl JsValue {
                 // v. If Type(result) is not Object, return result.
                 // vi. Throw a TypeError exception.
                 return if result.is_object() {
-                    Err(context.construct_type_error("Symbol.toPrimitive cannot return an object"))
+                    context.throw_type_error("Symbol.toPrimitive cannot return an object")
                 } else {
                     Ok(result)
                 };
@@ -465,33 +465,29 @@ impl JsValue {
     /// [spec]: https://tc39.es/ecma262/#sec-tobigint
     pub fn to_bigint(&self, context: &mut Context) -> JsResult<JsBigInt> {
         match self {
-            JsValue::Null => Err(context.construct_type_error("cannot convert null to a BigInt")),
+            JsValue::Null => context.throw_type_error("cannot convert null to a BigInt"),
-            JsValue::Undefined => {
+            JsValue::Undefined => context.throw_type_error("cannot convert undefined to a BigInt"),
-                Err(context.construct_type_error("cannot convert undefined to a BigInt"))
-            }
             JsValue::String(ref string) => {
                 if let Some(value) = JsBigInt::from_string(string) {
                     Ok(value)
                 } else {
-                    Err(context.construct_syntax_error(format!(
+                    context.throw_syntax_error(format!(
                         "cannot convert string '{}' to bigint primitive",
                         string
-                    )))
+                    ))
                 }
             }
             JsValue::Boolean(true) => Ok(JsBigInt::one()),
             JsValue::Boolean(false) => Ok(JsBigInt::zero()),
             JsValue::Integer(_) | JsValue::Rational(_) => {
-                Err(context.construct_type_error("cannot convert Number to a BigInt"))
+                context.throw_type_error("cannot convert Number to a BigInt")
             }
             JsValue::BigInt(b) => Ok(b.clone()),
             JsValue::Object(_) => {
                 let primitive = self.to_primitive(context, PreferredType::Number)?;
                 primitive.to_bigint(context)
             }
-            JsValue::Symbol(_) => {
+            JsValue::Symbol(_) => context.throw_type_error("cannot convert Symbol to a BigInt"),
-                Err(context.construct_type_error("cannot convert Symbol to a BigInt"))
-            }
         }
     }
 
@@ -522,9 +518,7 @@ impl JsValue {
             JsValue::Rational(rational) => Ok(Number::to_native_string(*rational).into()),
             JsValue::Integer(integer) => Ok(integer.to_string().into()),
             JsValue::String(string) => Ok(string.clone()),
-            JsValue::Symbol(_) => {
+            JsValue::Symbol(_) => context.throw_type_error("can't convert symbol to string"),
-                Err(context.construct_type_error("can't convert symbol to string"))
-            }
             JsValue::BigInt(ref bigint) => Ok(bigint.to_string().into()),
             JsValue::Object(_) => {
                 let primitive = self.to_primitive(context, PreferredType::String)?;
@@ -541,7 +535,7 @@ impl JsValue {
     pub fn to_object(&self, context: &mut Context) -> JsResult<JsObject> {
         match self {
             JsValue::Undefined | JsValue::Null => {
-                Err(context.construct_type_error("cannot convert 'null' or 'undefined' to object"))
+                context.throw_type_error("cannot convert 'null' or 'undefined' to object")
             }
             JsValue::Boolean(boolean) => {
                 let prototype = context.standard_objects().boolean_object().prototype();
@@ -859,13 +853,11 @@ impl JsValue {
         let integer_index = self.to_integer(context)?;
 
         if integer_index < 0.0 {
-            return Err(context.construct_range_error("Integer index must be >= 0"));
+            return context.throw_range_error("Integer index must be >= 0");
         }
 
         if integer_index > Number::MAX_SAFE_INTEGER {
-            return Err(
+            return context.throw_range_error("Integer index must be less than 2**(53) - 1");
-                context.construct_range_error("Integer index must be less than 2**(53) - 1")
-            );
         }
 
         Ok(integer_index as usize)
@@ -922,12 +914,8 @@ impl JsValue {
             JsValue::String(ref string) => Ok(string.string_to_number()),
             JsValue::Rational(number) => Ok(number),
             JsValue::Integer(integer) => Ok(f64::from(integer)),
-            JsValue::Symbol(_) => {
+            JsValue::Symbol(_) => context.throw_type_error("argument must not be a symbol"),
-                Err(context.construct_type_error("argument must not be a symbol"))
+            JsValue::BigInt(_) => context.throw_type_error("argument must not be a bigint"),
-            }
-            JsValue::BigInt(_) => {
-                Err(context.construct_type_error("argument must not be a bigint"))
-            }
             JsValue::Object(_) => {
                 let primitive = self.to_primitive(context, PreferredType::Number)?;
                 primitive.to_number(context)
@@ -962,7 +950,7 @@ impl JsValue {
     #[inline]
     pub fn require_object_coercible(&self, context: &mut Context) -> JsResult<&JsValue> {
         if self.is_null_or_undefined() {
-            Err(context.construct_type_error("cannot convert null or undefined to Object"))
+            context.throw_type_error("cannot convert null or undefined to Object")
         } else {
             Ok(self)
         }

boa/src/value/operations.rs

@@ -398,10 +398,10 @@ impl JsValue {
     pub fn instance_of(&self, target: &JsValue, context: &mut Context) -> JsResult<bool> {
         // 1. If Type(target) is not Object, throw a TypeError exception.
         if !target.is_object() {
-            return Err(context.construct_type_error(format!(
+            return context.throw_type_error(format!(
                 "right-hand side of 'instanceof' should be an object, got {}",
                 target.type_of()
-            )));
+            ));
         }
 
         // 2. Let instOfHandler be ? GetMethod(target, @@hasInstance).
@@ -419,7 +419,7 @@ impl JsValue {
             }
             None => {
                 // 4. If IsCallable(target) is false, throw a TypeError exception.
-                Err(context.construct_type_error("right-hand side of 'instanceof' is not callable"))
+                context.throw_type_error("right-hand side of 'instanceof' is not callable")
             }
         }
     }

boa/src/vm/mod.rs

@@ -225,10 +225,10 @@ impl Context {
                 let lhs = self.vm.pop();
 
                 if !rhs.is_object() {
-                    return Err(self.construct_type_error(format!(
+                    return self.throw_type_error(format!(
                         "right-hand side of 'in' should be an object, got {}",
                         rhs.type_of()
-                    )));
+                    ));
                 }
                 let key = lhs.to_property_key(self)?;
                 let value = self.has_property(&rhs, &key)?;
@@ -634,7 +634,7 @@ impl Context {
             }
             Opcode::Call => {
                 if self.vm.stack_size_limit <= self.vm.stack.len() {
-                    return Err(self.construct_range_error("Maximum call stack size exceeded"));
+                    return self.throw_range_error("Maximum call stack size exceeded");
                 }
                 let argc = self.vm.read::<u32>();
                 let mut args = Vec::with_capacity(argc as usize);
@@ -647,7 +647,7 @@ impl Context {
 
                 let object = match func {
                     JsValue::Object(ref object) if object.is_callable() => object.clone(),
-                    _ => return Err(self.construct_type_error("not a callable function")),
+                    _ => return self.throw_type_error("not a callable function"),
                 };
 
                 let result = object.__call__(&this, &args, self)?;
@@ -656,7 +656,7 @@ impl Context {
             }
             Opcode::CallWithRest => {
                 if self.vm.stack_size_limit <= self.vm.stack.len() {
-                    return Err(self.construct_range_error("Maximum call stack size exceeded"));
+                    return self.throw_range_error("Maximum call stack size exceeded");
                 }
                 let argc = self.vm.read::<u32>();
                 let mut args = Vec::with_capacity(argc as usize);
@@ -680,7 +680,7 @@ impl Context {
 
                 let object = match func {
                     JsValue::Object(ref object) if object.is_callable() => object.clone(),
-                    _ => return Err(self.construct_type_error("not a callable function")),
+                    _ => return self.throw_type_error("not a callable function"),
                 };
 
                 let result = object.__call__(&this, &args, self)?;
@@ -689,7 +689,7 @@ impl Context {
             }
             Opcode::New => {
                 if self.vm.stack_size_limit <= self.vm.stack.len() {
-                    return Err(self.construct_range_error("Maximum call stack size exceeded"));
+                    return self.throw_range_error("Maximum call stack size exceeded");
                 }
                 let argc = self.vm.read::<u32>();
                 let mut args = Vec::with_capacity(argc as usize);
@@ -707,7 +707,7 @@ impl Context {
             }
             Opcode::NewWithRest => {
                 if self.vm.stack_size_limit <= self.vm.stack.len() {
-                    return Err(self.construct_range_error("Maximum call stack size exceeded"));
+                    return self.throw_range_error("Maximum call stack size exceeded");
                 }
                 let argc = self.vm.read::<u32>();
                 let mut args = Vec::with_capacity(argc as usize);
@@ -854,10 +854,10 @@ impl Context {
             Opcode::ValueNotNullOrUndefined => {
                 let value = self.vm.pop();
                 if value.is_null() {
-                    return Err(self.construct_type_error("Cannot destructure 'null' value"));
+                    return self.throw_type_error("Cannot destructure 'null' value");
                 }
                 if value.is_undefined() {
-                    return Err(self.construct_type_error("Cannot destructure 'undefined' value"));
+                    return self.throw_type_error("Cannot destructure 'undefined' value");
                 }
                 self.vm.push(value);
             }

boa_tester/src/exec/js262.rs

@@ -67,7 +67,7 @@ fn detach_array_buffer(
 
     // 3. If SameValue(arrayBuffer.[[ArrayBufferDetachKey]], key) is false, throw a TypeError exception.
     if !JsValue::same_value(&array_buffer.array_buffer_detach_key, key) {
-        return Err(context.construct_type_error("Cannot detach array buffer with different key"));
+        return context.throw_type_error("Cannot detach array buffer with different key");
     }
 
     // 4. Set arrayBuffer.[[ArrayBufferData]] to null.

boa_wasm/src/lib.rs

@@ -11,10 +11,7 @@ pub fn evaluate(src: &str) -> Result<String, JsValue> {
         Err(e) => {
             return Err(format!(
                 "Uncaught {}",
-                context
+                context.construct_syntax_error(e.to_string()).display()
-                    .throw_syntax_error(e.to_string())
-                    .expect_err("interpreter.throw_syntax_error() did not return an error")
-                    .display()
             )
             .into());
         }