support invalid handle exception from rclpy in the action LoadComposableNodes

[firemark]

When the shutdown event will be invoked while loading nodes into a composable node then is a high change to raise rclpy.InvalidHandle exception. My pull request fixes that.

But ain't sure is a good way - maybe is not a problem here but in rclpy?

In my opinion in this code should be return self.context.ok() and self.service_is_ready() similar to the above line while ….

Maybe is a problem with priority - the ros node in the launcher shouldn't be turned off before running coroutines. But I don't know is easy to fix that (or is this a current case).

Steps to reproduce the bug

1. Create a file "test.launch.py"

Code

from launch_ros.descriptions import ComposableNode
from launch_ros.actions import ComposableNodeContainer, Node
from launch.actions import Shutdown
from launch import LaunchDescription


def generate_launch_description():
    return LaunchDescription(
        [
            ComposableNodeContainer(
                name="demo",
                namespace="",
                package="rclcpp_components",
                executable="component_container",
                output="both",
                composable_node_descriptions=create_nodes(),
          ),
          Shutdown(reason="¯\_(ツ)_/¯"),
      ]
  )

def create_nodes():
  return [
      ComposableNode(
          package="demo_nodes_cpp",
          plugin="demo_nodes_cpp::Listener",
          name="listener",
          namespace="/",
      ),
      ComposableNode(
          package="demo_nodes_cpp",
          plugin="demo_nodes_cpp::Talker",
          name="talker",
          namespace="/",
      ),
  ]

2. Run ros2 test.launch.py

Before fix

[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [component_container-1]: process started with pid [58172]
[component_container-1] [INFO] [1706798578.381711999] [demo]: Load Library: /opt/ros/humble/lib/libtopics_library.so
[component_container-1] [INFO] [1706798578.397282248] [demo]: Found class: rclcpp_components::NodeFactoryTemplate<demo_nodes_cpp::ContentFilteringPublisher>
[component_container-1] [INFO] [1706798578.397331365] [demo]: Found class: rclcpp_components::NodeFactoryTemplate<demo_nodes_cpp::ContentFilteringSubscriber>
[component_container-1] [INFO] [1706798578.397347057] [demo]: Found class: rclcpp_components::NodeFactoryTemplate<demo_nodes_cpp::Listener>
[component_container-1] [INFO] [1706798578.397358232] [demo]: Instantiate class: rclcpp_components::NodeFactoryTemplate<demo_nodes_cpp::Listener>
[INFO] [component_container-1]: sending signal 'SIGINT' to process[component_container-1]
[component_container-1] [INFO] [1706798578.618317891] [rclcpp]: signal_handler(signum=2)
[INFO] [component_container-1]: process has finished cleanly [pid 58172]
[WARNING] [launch_ros.actions.load_composable_nodes]: Abandoning wait for the '/demo/_container/load_node' service response, due to shutdown.
Future exception was never retrieved
future: <Future finished exception=InvalidHandle('cannot use Destroyable because destruction was requested')>
Traceback (most recent call last):
  File "/usr/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/actions/load_composable_nodes.py", line 197, in _load_in_sequence
    self._load_node(next_load_node_request, context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/actions/load_composable_nodes.py", line 119, in _load_node
    while not self.__rclpy_load_node_client.wait_for_service(timeout_sec=1.0):
  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/client.py", line 180, in wait_for_service
    return self.service_is_ready()
  File "/opt/ros/humble/local/lib/python3.10/dist-packages/rclpy/client.py", line 159, in service_is_ready
    with self.handle:
rclpy._rclpy_pybind11.InvalidHandle: cannot use Destroyable because destruction was requested

After fix

[INFO] [launch]: Default logging verbosity is set to INFO
[INFO] [component_container-1]: process started with pid [7864]
[component_container-1] [ERROR] [1706807191.272317427] [demo]: Could not find requested resource in ament index
[INFO] [component_container-1]: sending signal 'SIGINT' to process[component_container-1]
[component_container-1] [INFO] [1706807191.276060981] [rclcpp]: signal_handler(signum=2)
[INFO] [component_container-1]: process has finished cleanly [pid 7864]
[WARNING] [launch_ros.actions.load_composable_nodes]: Abandoning wait for the '/demo/_container/load_node' service response, due to shutdown.
[WARNING] [launch_ros.actions.load_composable_nodes]: Abandoning wait for the '/demo/_container/load_node' service, due to invalid rclpy handle.