[clang] [Clang] prevent assertion failure when converting vectors to int/float with invalid expressions (PR #105727)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

Thank you for the fix, can you add more details to the summary, in this case some details on the fix and why it works would be helpful.

https://github.com/llvm/llvm-project/pull/105727