[js-api] Fix ToValueType error case

[Liedtke]

Any invalid / unsupported string should run into this, so this shouldn't be an assertion but an error?
I assume we don't need new tests as this should already be covered by https://github.com/WebAssembly/spec/blob/main/test/js-api/global/constructor.any.js#L82?

[Ms2ger]

Can you explain in which cases you think this can be reached? Note that the WebIDL layer ensures that a value of type ValueType is always one of the strings in the enum.

[Liedtke]

Note that the WebIDL layer ensures that a value of type ValueType is always one of the strings in the enum.

Thanks for pointing that out, I wasn't aware of that.
https://wasm-dsl.github.io/spectec/js-api/#idl-index defines the ValueType enum which the WebAssembly.Global uses.
Do I understand correctly, that any invalid value not specified by the IDL is always reported as a TypeError and that is defined once for WebIDL and then implicitly relied on by the wasm-js spec?

[Ms2ger]

Indeed, when converting a javascript value to an enumeration type (https://webidl.spec.whatwg.org/#js-enumeration), any invalid values will cause an exception.

(Btw, you can use https://webassembly.github.io/spec/js-api again.)

[Liedtke]

Indeed, when converting a javascript value to an enumeration type (https://webidl.spec.whatwg.org/#js-enumeration), any invalid values will cause an exception.

Closing this PR as I was just missing context about how to read the spec, thank you for helping out!

(Btw, you can use https://webassembly.github.io/spec/js-api again.)

I updated my bookmark, thanks for the hint. :)