Bug report

The SimpleActionServer may call nullprt callback when executing the transition to deactivate if it is running and no completion callback is set.

Required Info:

• Operating System:
  • Ubuntu 20.04
• ROS2 Version:
  • ROS2 Iron
• Version or commit hash:
  • Latest Iron branch
• DDS implementation:
  • cycloneDDS

Steps to reproduce issue

Call lifecycle service transition "deactivate" when a lifecycle node with a simple action server is running.

Expected behavior

The SimpleActionServer doesn't call any callback.

Actual behavior

The SimpleActionServer does call a nullprt callback creating bad_function_call exception and the transition fails.

Additional information

The transition function catches a bad_function_call exception.
The deactivate() method will set `stop_execution_ = true;
https://github.com/ros-planning/navigation2/blob/c213c85c110f5f1d2b689c240ce84fb01eb430f5/nav2_util/include/nav2_util/simple_action_server.hpp#L299-L307

In the work() method, the code will call the completion_callback_ callback, but by default, this callback is nullptr.
https://github.com/ros-planning/navigation2/blob/c213c85c110f5f1d2b689c240ce84fb01eb430f5/nav2_util/include/nav2_util/simple_action_server.hpp#L262-L267

https://github.com/ros-planning/navigation2/blob/c213c85c110f5f1d2b689c240ce84fb01eb430f5/nav2_util/include/nav2_util/simple_action_server.hpp#L64-L68