Exception when calling /rosapi/node_details service with node name that doesn't exist

[ben-congram]

Description

Rosbridge crashes with TypeError: cannot unpack non-iterable NoneType object at this line when the node details service is called with a node name that doesn't exist. In practice, I've see this happen when nodes are stopping and starting frequently and a node is shutdown just before this call is made. However, it is easier to reproduce by calling the service manually.

Should be a simple fix to check the return value is not None before unpacking it.

• Library Version: 1.3.1
• ROS Version: ROS2 Humble
• Platform / OS: Ubuntu 22.04.2 LTS

Steps To Reproduce

• ros2 launch rosbridge_server rosbridge_websocket_launch.xml
• ros2 service call /rosapi/node_details rosapi_msgs/srv/NodeDetails "node: /not_a_real_node"

Expected Behavior

• Some response to service call
• Rosbridge websocket continues working normally

Actual Behavior

• rosapi_node dies after TypeError
• Service call hangs