[clang] [Clang] Fix an incorrect assumption on getTemplatedDecl() (PR #131559)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

> Thank you for the quick fix, I would have also added the test that did not crash but issued a diagnostic from the issue as well: #131530
> 
> unless we have a similar test already.

Yeah, probably it merits a followup NFC patch



https://github.com/llvm/llvm-project/pull/131559