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

[Oleksandr T. via cfe-commits]

a-tarasyuk wrote:

@AaronBallman could you review these changes? https://github.com/llvm/llvm-project/issues/105486#issuecomment-2308879407 thanks

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