[clang-tools-extra] [clang-tidy] Fix for cppcoreguidelines-pro-type-union-access if memLoc is invalid (PR #104540)

[Konstantin Romanov via cfe-commits]

ksromanov wrote:

> This is still missing a release note, see

Many thanks! This is my first PR to `llvm`, I didn't know about it, sorry.

https://github.com/llvm/llvm-project/pull/104540