Summary:
We got a few crash reports where LLDB crashes while derefencing the `frames_value` shared_ptr in the AppleObjCRuntime::GetBacktraceThreadFromException. `GetChildMemberWithName` returns a nullptr when an error occurs, so this seems to be just a missing nullptr check.
This patch adds that nullptr check and the other ones in the similar code directly below.
Fixes rdar://62174039
Reviewers: jingham, kubamracek
Reviewed By: jingham
Subscribers: abidh, JDevlieghere
Differential Revision: https://reviews.llvm.org/D78798
f8af9f5fca