[clang] [NFC][Clang] Fix static analyzer bugs with dereference after null checks (PR #86018)

[via cfe-commits]

smanna12 wrote:

> If you read the code, it should be obvious the pointer is in fact non-null. Please don't insert null checks into the code just to address static analyzer false positives.

Thank you @efriedma-quic for reviews! I misunderstood some of the code parts.  

https://github.com/llvm/llvm-project/pull/86018