[clang] [Clang][Sema] Check null after ExtractTypeForDeductionGuide (PR #165776)

[Mariya Podchishchaeva via cfe-commits]

https://github.com/Fznamznon commented:

Thank you for working on this, could you please add a release note?

https://github.com/llvm/llvm-project/pull/165776