Distinguish explicity thrown WASM errors in JS

[poorna2152]

Explicitly thrown errors uses a tag to distinguish them. For example for,

• integer overflow: (throw $overflow)
• bad casting: (throw $bad-casting)

But the error message emitted in the JS does not contain this tag thus it cannot distinguish between explicitly thrown errors https://github.com/WebAssembly/exception-handling/blob/main/proposals/exception-handling/Exceptions.md

[poorna2152]

It is possible to do this by,

1. Exporting the tags from the WASM module
2. If an exception is thrown and check if it is of type WebAssembly.Exception.
3. If so pass the exported tags one by one to the err.is(tag) function in WebAssembly.Exception class. Function returns true when a matching tag is found