Uncaught ReferenceError error in abort (preamble.js) when WebAssembly is not available

[localpcguy]

The abort method in preamble.js tries to use WebAssembly to create a RuntimeError and crashes with an Uncaught ReferenceError when WebAssembly is not available. Looking at the history, this used to be wrapped in a check for WASM, but once fastcomp was removed, that check would always be true, and so the check was removed.

My question is, is it intentional for it to fail with an Uncaught ReferenceError: WebAssembly is not available or was that a side effect of WASM being true and then being removed? It does seem per the original intent that there should be an error thrown at this point to exit/abort the script, so would any fix just end up throwing a manually crafted error instead of failing due to WebAssembly being undefined?

This error is currently seen when using Rive-Canvas, which using emscripten, if I don't check for WebAssembly support prior to trying to use their code.

[kripken]

Is this in a debug or release build?

In a debug build we should make sure we have a clear error for this. If we don't have one we should add one.

In a release build that targets wasm (i.e. not wasm2js) we do not generally add to the output size in order to get nicer error messages. Running such a build on a VM without the WebAssembly object would be a such a case, I think - not worth adding to size for, in release.

[localpcguy]

I believe it is in a release build. I agree it would be nice to have a clear error in a debug build, if nothing else, it would make it clear when reading that code that it is throwing intentionally and is not an error that requires resolution.