UnboundLocalError: local variable 'inputs' referenced before assignment

The below error is encountered during **finetuning of pretrained model with AVA dataset**. It is happening because of line 89 **enumerate(train_loader)** in tools/train_net.py is empty. But I am not sure why this is empty.

***
Traceback (most recent call last):
File "tools/run_net.py", line 45, in
main()
File "tools/run_net.py", line 26, in main
launch_job(cfg=cfg, init_method=args.init_method, func=train)
File "/activty_recognizer/slowfast/slowfast/utils/misc.py", line 311, in launch_job
func(cfg=cfg)
File "/activty_recognizer/ava_training/SlowFast/tools/train_net.py", line 714, in train
train_epoch(
File "/activty_recognizer/ava_training/SlowFast/tools/train_net.py", line 265, in train_epoch
del inputs
UnboundLocalError: local variable 'inputs' referenced before assignment
***
**But train_loader has this data:**
{'dataset': , 'num_workers': 2, 'prefetch_factor': 2, 'pin_memory': True, 'timeout': 0, 'worker_init_fn': None, '_DataLoader__multiprocessing_context': None, '_dataset_kind': 0, 'batch_size': 8, 'drop_last': True, 'sampler': , 'batch_sampler':, 'generator': None, 'collate_fn': , 'persistent_workers': False, '_DataLoader__initialized': True, '_IterableDataset_len_called': None, '_iterator': None}_