'PanopticFuseTrack' object has no attribute 'prev_bboxes'

[lxyzler]

python tools/test_vpq.py configs/cityscapes/fusetrack.py work_dirs/cityscapes_vps/fusetrack_vpct/latest.pth --out work_dirs/cityscapes_vps/fusetrack_vpct/test.pkl --pan_im_json_file data/cityscapes_vps/panoptic_im_val_city_vps.json --n_video 50 --mode test
/opt/sherry/lane_decetion/vps/tools/config/config.py:180: YAMLLoadWarning: calling yaml.load() without Loader=... is deprecated, as the default Loader is unsafe. Please read https://msg.pyyaml.org/load for full details.
exp_config = edict(yaml.load(f))
loading annotations into memory...
Done (t=1.01s)
creating index...
index created!
==> Inside PanopticFuseTrack (Device ID: 0)
--- Load flow module: /opt/sherry/lane_decetion/vps/work_dirs/flownet/FlowNet2_checkpoint.pth.tar
[ ] 0/500, elapsed: 0s, ETA:Traceback (most recent call last):
File "tools/test_vpq.py", line 203, in
main()
File "tools/test_vpq.py", line 153, in main
data_loader)
File "tools/test_vpq.py", line 46, in single_gpu_test
result = model(return_loss=False, rescale=not show, **data)
File "/opt/sherry/.local/lib/python3.6/site-packages/torch/nn/modules/module.py", line 532, in call
result = self.forward(*input, **kwargs)
File "/opt/sherry/.local/lib/python3.6/site-packages/torch/nn/parallel/data_parallel.py", line 150, in forward
return self.module(*inputs[0], **kwargs[0])
File "/opt/sherry/.local/lib/python3.6/site-packages/torch/nn/modules/module.py", line 532, in call
result = self.forward(*input, **kwargs)
File "/opt/sherry/lane_decetion/vps/mmdet/core/fp16/decorators.py", line 49, in new_func
return old_func(*args, **kwargs)
File "/opt/sherry/lane_decetion/vps/mmdet/models/detectors/base.py", line 104, in forward
return self.forward_test(img, img_meta, **kwargs)
File "/opt/sherry/lane_decetion/vps/mmdet/models/detectors/base.py", line 95, in forward_test
return self.simple_test(imgs[0], img_metas[0], **kwargs)
File "/opt/sherry/lane_decetion/vps/mmdet/models/detectors/panoptic_fusetrack.py", line 543, in simple_test
rescale=rescale, is_panoptic=True)
File "/opt/sherry/lane_decetion/vps/mmdet/models/detectors/panoptic_fusetrack.py", line 400, in simple_test_bboxes
if is_first or (not is_first and self.prev_bboxes is None):
File "/opt/sherry/.local/lib/python3.6/site-packages/torch/nn/modules/module.py", line 576, in getattr
type(self).name, name))
AttributeError: 'PanopticFuseTrack' object has no attribute 'prev_bboxes'

how to solve it

my environment:
gcc version 5.4.0 (GCC)
CUDA Version: 10.1
torch.version '1.4.0'