ROS 2 Humble SimpleActionState is stuck

[amock]

I encountered an issue where the SimpleActionState was waiting endlessly for a response from the action server, around line ~368:

# Wait for action to finish
self._done_cond.wait()

To address this, I modified the code as follows:

self._goal_result = None

# [...]

# Wait for action to finish
while self._goal_result is None:
    rclpy.spin_once(self.node)
    time.sleep(0.01)

My guess: Perhaps the issue is that the node isn't spinning while it's waiting for the condition to be met. As a result, it doesn't process any incoming responses from the action server, so the notify function never gets called.

Anyways, this change seems to resolve the issue, but I'm not entirely sure if this solution is the best one.