[lldb][TypeSystemClang] Avoid accessing definition if none is available#9217

Michael137 merged 1 commit intostable/20240723swiftlang/llvm-project:stable/20240723from

bugfix/lldb-def-crash-to-20240723swiftlang/llvm-project:bugfix/lldb-def-crash-to-20240723Copy head branch name to clipboard