plot_skeleton_state with Nothing

[mxllc]

https://github.com/NVIDIA-Omniverse/IsaacGymEnvs/blob/665c32170d84b4be66722eea405a1e08b6e7f761/isaacgymenvs/tasks/amp/poselib/generate_amp_humanoid_tpose.py#L63

Hi, I run the generate_amp_humanoid_tpose.py file, and got the following screen output with a full white image.
What's wrong with it?

2023-08-06 00:35:44,867 - INFO - logger - logger initialized
2023-08-06 00:35:45,276 - INFO - common - plotting