No activity on the field

[gerrich]

I run the environment with standard tool:

python3 examples/scripts/sim_env --mode random  SoccerEmptyGoal-v0

Soccer field is displayed in separate window, but where is no activity.

There are also many error messages in console:
0: error: Illegal player side. . 0 ".5741 -0.9172 0 0) ((l 1) 0 0 -3 -37 -0 -0 0 0 (v h 90) (s 8000 1 1 130600) ...

Is that a correct way to use the environment?