ros noetic 运行roslaunch mbot_gazebo view_mbot_gazebo_empty_world.launch时，出现一下错误

RLException: Invalid <arg> tag: arg ‘debug’ has already been declared.

Arg xml is <arg name=”debug” value=”$(arg debug)”/>
The traceback for the exception was written to the log file

 

请问一下问题出在哪里?