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

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

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: https://github.com/llvm/llvm-project/issues/131530

unless we have a similar test already.

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