TypeError: object of type 'NoneType' has no len()

Dear Team,

I am trying to run the demo but I able to run and dump the output properly with SLOWFAST_32x2_R101_50_50.pkl (Pytorch AVA model) but with I3D_NLN_8x8_R50.pkl model (Caffe2 Kinetic model) I am getting this error "TypeError: object of type 'NoneType' has no len()" on same sample video. Putting the complete error flow for your reference:

[INFO: checkpoint.py: 239]: res4_3_branch2b_bn_b: (256,) => s4.pathway0_res3.branch2.b_bn.bias: (256,)
[08/06 19:52:10][INFO] slowfast.utils.checkpoint: 239: res4_3_branch2b_bn_b: (256,) => s4.pathway0_res3.branch2.b_bn.bias: (256,)
[INFO: checkpoint.py: 239]: res4_5_branch2a_bn_b: (256,) => s4.pathway0_res5.branch2.a_bn.bias: (256,)
[08/06 19:52:10][INFO] slowfast.utils.checkpoint: 239: res4_5_branch2a_bn_b: (256,) => s4.pathway0_res5.branch2.a_bn.bias: (256,)
[INFO: predictor.py: 38]: Finish loading model weights
[08/06 19:52:10][INFO] slowfast.visualization.predictor: 38: Finish loading model weights
[ERROR: video_visualizer.py: 32]: Class indices get out of range: [189]
[08/06 19:52:10][ERROR] slowfast.visualization.video_visualizer: 32: Class indices get out of range: [189]
0it [00:10, ?it/s]
Traceback (most recent call last):
File "tools/run_net.py", line 39, in
main()
File "tools/run_net.py", line 35, in main
demo(cfg)
File "/data/priyabrata/video_analytics/action_understanding/slowfast_V2/SlowFast/tools/demo_net.py", line 98, in demo
for frames in tqdm.tqdm(run_demo(cfg, frame_provider)):
File "/data/slowfast/lib/python3.7/site-packages/tqdm/std.py", line 1130, in __iter__
for obj in iterable:
File "/data/priyabrata/video_analytics/action_understanding/slowfast_V2/SlowFast/tools/demo_net.py", line 75, in run_demo
frames = draw_predictions(task, video_vis)
File "/data/priyabrata/video_analytics/action_understanding/slowfast_V2/SlowFast/slowfast/visualization/predictor.py", line 189, in draw_predictions
frames, preds, keyframe_idx=keyframe_idx, draw_range=draw_range
File "/data/priyabrata/video_analytics/action_understanding/slowfast_V2/SlowFast/slowfast/visualization/video_visualizer.py", line 522, in draw_clip_range
+ list(right_frames)
File "/data/priyabrata/video_analytics/action_understanding/slowfast_V2/SlowFast/slowfast/visualization/video_visualizer.py", line 585, in draw_clip
ground_truth=ground_truth,
File "/data/priyabrata/video_analytics/action_understanding/slowfast_V2/SlowFast/slowfast/visualization/video_visualizer.py", line 468, in draw_one_frame
alpha=text_alpha,
File "/data/priyabrata/video_analytics/action_understanding/slowfast_V2/SlowFast/slowfast/visualization/video_visualizer.py", line 141, in draw_multiple_text
text_ls
TypeError: object of type 'NoneType' has no len()

Kindly help me to resolve this issue. Thanks in Advance.