AssertionError: datasets should not be an empty iterable when I run in deep-text-recognition-benchmark

    !python train.py --train_data lmdb_output --valid_data lmdb_output --select_data "/" --        batch_ratio 1.0 --Transformation TPS --FeatureExtraction ResNet --SequenceModeling BiLSTM --Prediction Attn --batch_size 2 --data_filtering_off --workers 0 --batch_max_length 80 --num_iter 10 --valInterval 5 --saved_model TPS-ResNet-BiLSTM-Attn.pth  

   Full error:
Traceback (most recent call last):
File "/content/deep-text-recognition-benchmark/train.py", line 317, in
train(opt)
File "/content/deep-text-recognition-benchmark/train.py", line 31, in train
train_dataset = Batch_Balanced_Dataset(opt)
File "/content/deep-text-recognition-benchmark/dataset.py", line 42, in init
_dataset, _dataset_log = hierarchical_dataset(root=opt.train_data, opt=opt, select_data=[selected_d])
File "/content/deep-text-recognition-benchmark/dataset.py", line 124, in hierarchical_dataset
concatenated_dataset = ConcatDataset(dataset_list)
File "/usr/local/lib/python3.10/dist-packages/torch/utils/data/dataset.py", line 317, in init
assert len(self.datasets) > 0, 'datasets should not be an empty iterable' # type: ignore[arg-type]
AssertionError: datasets should not be an empty iterable