When I train crnn ,it had an error，how should I solve this problem?
Traceback (most recent call last):
File “crnn/crnn_main.py”, line 212, in 
cost = trainBatch(crnn, criterion, optimizer)
File “crnn/crnn_main.py”, line 191, in trainBatch
t, l = converter.encode(gpu_texts)
File “/home/yang/Scence_Recognition/crnn/utils.py”, line 66, in encode
return (torch.IntTensor(text), torch.IntTensor(length))
RuntimeError: tried to construct a tensor from a int sequence, but found an item of type NoneType at index (0)