[llvm] [WebAssembly] Support assembly parsing for new EH (PR #108668)

[Heejin Ahn via llvm-commits]

aheejin wrote:

> Any thoughts on what might be the most likely error cases to arise in practice? I noticed there are no tests of error cases; I don't think I'd necessarily want to try to be really comprehensive on covering every possible error cases but if we think some categories are more likely, it might be good to have something.

Added some error cases.

Tried to check an invalid tag too, but that's a realm of AsmTypeCheck.

https://github.com/llvm/llvm-project/pull/108668