cmake with error code 1 during second build

[vsundar31]

During the second build instruction under the 4.2 gazebo and SLAM in the readme, my build fails since gf_orb_slam2 has a cmake error with code 1 and exits, which leads to others being abandoned. I tried ignoring this, but I can't run gazebo without it.

[duyanwei]

Please post your error, so that we will know what happens exactly.
Additionally, what is meant by 'can’t run Gazebo without it'? The Gazebo simulator operates independently of any SLAM systems.
The closedloop benchmark requires you to install whichever the SLAM you want to test, or you can implement your own SLAM for testing.