[clang-tidy] Fix crash in --dump-config

Fixes a crash in dump-config when checks emit warnings trying to read the config

Fixes https://github.com/llvm/llvm-project/issues/50876



Co-authored-by: Piotr Zegar <me@piotrzegar.pl>

Reviewed By: PiotrZSL

Differential Revision: https://reviews.llvm.org/D148436