ros_control_demo example view_robot.launch.py fails to launch

edit

Hi everyone, its my first post here so forgive me if i miss any details out.

I've followed the instructions here: https://docs.ros.org/en/humble/Instal..., to install ros2 humble.

i've further installed ros-humble-ros2-control & ros-humble-ros2-controllers

To recreate the issue I created my workspace:

mkdir -p robot_ws/src

from this link: https://github.com/ros-controls/ros2_..., i cloned the humble branch and copied over example 2 to the src directory.

I then built the workspace:

cd robot_ws
colcon build --symlink-install

After the build finished i sourced the workspace (i have ros2 sourced in .bashrc prior to this) and tried to launch view_robot.launch.py:

source install/setup.bash
ros2 launch ros2_control_demo_example_2 view_robot.launch.py --debug

i receive the following:

[DEBUG] [launch.launch_context]: emitting event synchronously: 'launch.events.IncludeLaunchDescription'
[INFO] [launch]: All log files can be found below /home/oscar/.ros/log/2023-05-30-01-54-21-996563-oscar-ROG-Zephyrus-G14-GA401QE-GA401QE-41111
[INFO] [launch]: Default logging verbosity is set to DEBUG
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7fea18887b20>'
[DEBUG] [launch]: processing event: '<launch.events.include_launch_description.IncludeLaunchDescription object at 0x7fea18887b20>' ✓ '<launch.event_handlers.on_include_launch_description.OnIncludeLaunchDescription object at 0x7fea19229030>'
[DEBUG] [launch]: An exception was raised in an async action/event
[DEBUG] [launch]: Traceback (most recent call last):
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 336, in run_async
    raise completed_tasks_exceptions[0]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 230, in _process_one_event
    await self.__process_event(next_event)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/launch_service.py", line 250, in __process_event
    visit_all_entities_and_collect_futures(entity, self.__context))
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 45, in visit_all_entities_and_collect_futures
    futures_to_return += visit_all_entities_and_collect_futures(sub_entity, context)
  [Previous line repeated 1 more time]
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/visit_all_entities_and_collect_futures_impl.py", line 38, in visit_all_entities_and_collect_futures
    sub_entities = entity.visit(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/action.py", line 108, in visit
    return self.execute(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/actions/node.py", line 490, in execute
    self._perform_substitutions(context)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/actions/node.py", line 445, in _perform_substitutions
    evaluated_parameters = evaluate_parameters(context, self.__parameters)
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/utilities/evaluate_parameters.py", line 164, in evaluate_parameters
    output_params.append(evaluate_parameter_dict(context, param))
  File "/opt/ros/humble/lib/python3.10/site-packages/launch_ros/utilities/evaluate_parameters.py", line 72, in evaluate_parameter_dict
    evaluated_value = perform_substitutions(context, list(value))
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/perform_substitutions_impl.py", line 26, in perform_substitutions
    return ''.join([context.perform_substitution(sub) for sub in subs])
  File "/opt/ros/humble/lib/python3.10/site-packages/launch/utilities/perform_substitutions_impl.py", line 26, in <listcomp>
    return ''.join([context.perform_substitution(sub) for sub in subs])
  File "/opt/ros/humble/lib ...