Found an issue where we might still have shared pointer references to lldb_private::Thread objects where the object itself is not valid and has been removed from the Process. When a thread is removed from a process, it will call Thread::DestroyThread() which well set a boolean member variable which is exposed now via:
bool
Thread::IsValid() const;
We then check the thread validity before handing out a shared pointer.
llvm-svn: 154048