src/hotspot/share/runtime/javaCalls.cpp

JavaCallWrapper::JavaCallWrapper(const methodHandle& callee_method, Handle receiver, JavaValue* result, TRAPS) {
  JavaThread* thread = THREAD;
...
 ThreadStateTransition::transition_from_vm(thread, _thread_in_Java, true /* check_asyncs */);
...
 _thread = thread;
...
 assert (_thread->thread_state() != _thread_in_native, "cannot set native pc to NULL");

The assertion is redundant as we previously set the state to _thread_in_Java.