This is an experiment that tries to migrate the codebase from eager `Error` objects to lazy ones.
In short words, this redefines `JsResult = Result<JsValue, JsError>`, where `JsError` is a brand new type that stores only the essential part of an error type, and only transforms those errors to `JsObject`s on demand (when having to pass them as arguments to functions or store them inside async/generators).
This change is pretty big, because it unblocks a LOT of code from having to take a `&mut Context` on each call. It also paves the road for possibly making `JsError` a proper variant of `JsValue`, which can be a pretty big optimization for try/catch.
A downside of this is that it exposes some brand new error types to our public API. However, we can now implement `Error` on `JsError`, making our `JsResult` type a bit more inline with Rust's best practices.
~Will mark this as draft, since it's missing some documentation and a lot of examples, but~ it's pretty much feature complete. As always, any comments about the design are very much appreciated!
Note: Since there are a lot of changes which are essentially just rewriting `context.throw` to `JsNativeError::%type%`, I'll leave an "index" of the most important changes here:
- [boa_engine/src/error.rs](https://github.com/boa-dev/boa/pull/2283/files#diff-f15f2715655440626eefda5c46193d29856f4949ad37380c129a8debc6b82f26)
- [boa_engine/src/builtins/error/mod.rs](https://github.com/boa-dev/boa/pull/2283/files#diff-3eb1e4b4b5c7210eb98192a5277f5a239148423c6b970c4ae05d1b267f8f1084)
- [boa_tester/src/exec/mod.rs](https://github.com/boa-dev/boa/pull/2283/files#diff-fc3d7ad7b5e64574258c9febbe56171f3309b74e0c8da35238a76002f3ee34d9)
José Julián Espina
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