[clang] [clang] fix sema init crash for not checking a ExprResult (PR #98102)

[Yuxuan Chen via cfe-commits]

yuxuanchen1997 wrote:

@AaronBallman I have good news. I was able to manually write a well-formed C++ file that crashes. https://gist.github.com/yuxuanchen1997/576dce964666f0f8713fccacf5847138

And I am able to validate that the fix I proposed here does fix the problem. 

https://github.com/llvm/llvm-project/pull/98102