[llvm] [GlobalISel] Diagnose inline assembly constraint lowering errors (PR #135782)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> I added some tests, do you want me to test every message? 

Comprehensive tests are always best 

> It might be difficult because a few situations crash the DAG as well, they're cases that are unsupported in general

Should fix those too



https://github.com/llvm/llvm-project/pull/135782