Throw a type error when a non-object is called (#561)

boa/src/exec/mod.rs

@@ -173,7 +173,7 @@ impl Interpreter {
                 }
                 self.throw_type_error("not a function")
             }
-            _ => Err(Value::undefined()),
+            _ => self.throw_type_error("not a function"),
         }
     }
 

boa/src/exec/tests.rs

@@ -1128,3 +1128,38 @@ fn check_this_binding_in_object_literal() {
 
     assert_eq!(forward(&mut engine, init), "8");
 }
+
+#[test]
+fn not_a_function() {
+    let realm = Realm::create();
+    let mut engine = Interpreter::new(realm);
+    let init = r#"
+        let a = {};
+        let b = true;
+        "#;
+    forward(&mut engine, init);
+    let scenario = r#"
+        try {
+            a();
+        } catch(e) {
+            e.message
+        }
+    "#;
+    assert_eq!(forward(&mut engine, scenario), "not a function");
+    let scenario = r#"
+        try {
+            a.a();
+        } catch(e) {
+            e.message
+        }
+    "#;
+    assert_eq!(forward(&mut engine, scenario), "not a function");
+    let scenario = r#"
+        try {
+            b();
+        } catch(e) {
+            e.message
+        }
+    "#;
+    assert_eq!(forward(&mut engine, scenario), "not a function");
+}