[llvm] [SelectionDAG] Fix null pointer dereference in resolveDanglingDebugInfo (PR #174341)

[Benjamin Maxwell via llvm-commits]

MacDue wrote:

It looks like logic was to document a crash, but it's probably much better to raise an issue with the reproducer. It seems like a `good-first-issue`. 

https://github.com/llvm/llvm-project/pull/174341