[llvm] [llvm] Fix potential null dereference in IR/Verifier (PR #157458)

[Ramkumar Ramachandra via llvm-commits]

https://github.com/artagnon commented:

Please update the PR title/description. Suffix the title with "(NFC)" to make it clear that the change is non-functional.

https://github.com/llvm/llvm-project/pull/157458