Objects with getters that fail do not trigger an error

[Arshia001]

In the implementation of ion::Object::get:

spiderfire/ion/src/object/object.rs

Lines 83 to 99 in 74a68bb

	pub fn get<'cx, K: ToPropertyKey<'cx>>(&self, cx: &'cx Context, key: K) -> Option<Value<'cx>> {
	let key = key.to_key(cx).unwrap();
	if self.has(cx, &key) {
	let mut rval = Value::undefined(cx);
	unsafe {
	JS_GetPropertyById(
	cx.as_ptr(),
	self.handle().into(),
	key.handle().into(),
	rval.handle_mut().into(),
	)
	};
	Some(rval)
	} else {
	None
	}
	}

The return value of JS_GetPropertyById is not checked, so an object with a getter that fails does not propagate the error. This may also be the case for other calls into SpiderMonkey, but I haven't checked for more.

For context, this is the WPT test that fails as a result of this:

    test(() => {
      assert_throws_js(
        () => new TextDecoderStream('utf-8', {
          get fatal() { throw new Error(); }
        }), 'the constructor should throw');
    }, 'a throwing fatal member should cause the constructor to throw');

Note, the TextDecoderStream implementation is local to WinterJS and I put the test here just to illustrate the problem.

[Arshia001]

@Redfire75369 the current implementation of get_as after fixing this issue causes conversion of null to Option<*mut JSObject> to fail. This is probably the correct implementation:

	/// Gets the value at the given key of the [Object]. as a Rust type.
	/// Returns [None] if the object does not contain the key or conversion to the Rust type fails.
	pub fn get_as<'cx, K: ToPropertyKey<'cx>, T: FromValue<'cx>>(
		&self, cx: &'cx Context, key: K, strict: bool, config: T::Config,
	) -> Result<Option<T>> {
		Ok(self.get(cx, key)?.and_then(|val| T::from_value(cx, &val, strict, config).ok()))
	}