[compiler-rt] [sanitizer] add null check (PR #105612)

[Wu Yingcong via llvm-commits]

yingcong-wu wrote:

Sure, that makes sense. So is the idea that if some follow-up action leads to some fatal errors like segment fault, then we can skip the assertion because those fatal errors basically act as assertions?

https://github.com/llvm/llvm-project/pull/105612