[clang] [clang][analyzer] fix crash when modelling 'getline' function in checkers (PR #145229)

[Balazs Benics via cfe-commits]

https://github.com/steakhal approved this pull request.

I have one question remaining, but it's already great.
Thank you for fixing this crash!

https://github.com/llvm/llvm-project/pull/145229