[clang] [Clang] Fixed a crash when instantiating an invalid out-of-line static data member definition in a local class (PR #196772)

[Oliver Hunt via cfe-commits]

ojhunt wrote:

@TPPPP72 sorry, so this is what I meant previously: the other assertion could have been the result of an existing error: other code failing to invalidate the decl when it should have, and then other code never having to have considered the potential that it was operating on an already invalid decl. You pointed to the decl saying it was not invalid as evidence of it not being invalid without considering that the same error you originally fixed could have been happening there as well: an invalid decl (or anything else) not being recorded as invalid.

I apologize for not being as clear as I should have been.

https://github.com/llvm/llvm-project/pull/196772