Fix exceptions getting bulk_data.categories and plugins at startup

[nnarain]

Pull Request

Summary

After building and trying to run medkit gateway I had the follow exceptions

[gateway_node-1] terminate called after throwing an instance of 'rclcpp::exceptions::InvalidParameterValueException'
[gateway_node-1] what(): parameter_value_from failed for parameter 'bulk_data.categories': No parameter value set
[ERROR] [gateway_node-1]: process has died [pid 78467, exit code -6, cmd '/workspaces/ros_ws/install/ros2_medkit_gateway/lib/ros2_medkit_gateway/gateway_node --ros-args --log-level info --ros-args -r __node:=ros2_medkit_gateway --params-file /workspaces/ros_ws/install/ros2_medkit_gateway/share/ros2_medkit_gateway/config/gateway_params.yaml --params-fevel info --ros-args -r __node:=ros2_medkiile /tmp/launch_params_3pu02a64'].

of 'rclcpp::exceptions::InvalidParameterValueException'
[gateway_node-1] what(): parameter_value_from failed for parameter 'bulk_data.categories': No parameter value set
[ERROR] [gateway_node-1]: process has died [pid 102916, exit code -6, cmd '/workspaces/ros_ws/install/ros2_medkit_gateway/lib/ros2_medkit_gateway/gateway_node --ros-args --log-level info --ros-args -r __node:=ros2_medkit_gateway --params-file /workspaces/ros_ws/install/ros2_medkit_gateway/share/ros2_medkit_gateway/config/gateway_params.yaml --params-file /tmp/launch_params_y0pyhd4w'].

Looks like this is done in a few places, just not for these params.

https://github.com/selfpatch/ros2_medkit/blob/main/src/ros2_medkit_gateway/config/gateway_params.yaml#L322

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Issue

Link the related issue (required):

• closes [BUG] InvalidParameterValueException on gateway startup #255

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Type

• Bug fix
• New feature or tests
• Breaking change
• Documentation only

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Testing

ros2 launch ros2_medkit_gateway gateway.launch.py

Gateway started as expected.

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Checklist

• Breaking changes are clearly described (and announced in docs / changelog if needed)
• Tests were added or updated if needed
• Docs were updated if behavior or public API changed

[Copilot]

Pull request overview

This PR aims to prevent ROS 2 startup exceptions caused by parameters that are configured as empty arrays in gateway_params.yaml (notably bulk_data.categories and plugins), which can trigger InvalidParameterValueException during parameter file parsing.

Changes:

• Update bulk_data.categories default in gateway_params.yaml from [] to [""].
• Update plugins default in gateway_params.yaml from [] to [""].

[bburda]

LGTM +1 - thanks for the fix! 🚀

[bburda]

@nnarain could you please clang-format the code?

[nnarain]

Yup will do