Reject wrong lifecycle transitions without crash (ros2#1209)

Signed-off-by: Christian Bitter <cbi@circuli-ion.com>

rclpy/rclpy/lifecycle/node.py

@@ -350,6 +350,12 @@ def __on_change_state(
     ):
         self.__check_is_initialized()
         transition_id = req.transition.id
+
+        available_transition_ids = [t[0] for t in self._state_machine.available_transitions]
+        if transition_id not in available_transition_ids:
+              resp.success = False
+              return resp
+
         if req.transition.label:
             try:
                 transition_id = self._state_machine.get_transition_by_label(req.transition.label)