Gazebo simulation error with tag

[MieRobot]

Hi - The simulator throws error in Gazebo in second command. See attached file. The path are sourced and only the physics environment appear with first command.

First command roslaunch volta_simulation gazebo.launch (This one works)
Second command roslaunch volta_simulation simulation.launch (Shows the attached error)
ROS Version used is Melodic. Please help and see if this is a bug. Overall nice repo work.

[nikhil-botsync]

@MieRobot sorry for the delay on this..
The simulation launch file is cross dependant on the URDF description files.
Could you check after cloning the packages from here - https://github.com/botsync/volta ?