[lldb] Account for objc_debug_class_getNameRaw returning NULL

On macOS Catalina, calling objc_debug_class_getNameRaw on some of the
ISA pointers returns NULL, causing us to crash and unwind before reading
all the Objective-C classes. This does not happen on macOS Big Sur.
Account for that possibility and skip the class when that happens.

GitOrigin-RevId: cf51bf77b070f63391bacada5e166bfec2616989
1 file changed