trouble in datsets create

[biexiangduo]

Hi, I met problem in making datasets. I directly make segmentaion img by labelme ,and transfer segmentation img to 8 bit grayscale. data tree like following:
.
├── trainA
│   ├── 1.png
│   ├── 2.png
│   ├── 3.png
│   └── 4.png
├── trainA_seg
│   ├── 1.png
│   ├── 2.png
│   ├── 3.png
│   └── 4.png
├── trainB
│   ├── 1.png
│   ├── 2.png
│   ├── 3.png
│   └── 4.png
└── trainB_seg
├── 1.png
├── 2.png
├── 3.png
└── 4.png

the error:
verbose: False
----------------- End -------------------
dataset [UnalignedSegDataset] was created
#training images = 4
initialize network with normal
initialize network with normal
initialize network with normal
initialize network with normal
model [InstaGANModel] was created
---------- Networks initialized -------------
[Network G_A] Total number of parameters : 26.815 M
[Network G_B] Total number of parameters : 26.815 M
[Network D_A] Total number of parameters : 9.754 M
[Network D_B] Total number of parameters : 9.754 M

Setting up a new session...
create web directory ./checkpoints/_instagan/web...
Traceback (most recent call last):
File "train.py", line 24, in
for i, data in enumerate(dataset):
File "/home/pf/instagan/data/init.py", line 72, in iter
for i, data in enumerate(self.dataloader):
File "/home/pf/anaconda3/lib/python3.6/site-packages/torch/utils/data/dataloader.py", line 286, in next
return self._process_next_batch(batch)
File "/home/pf/anaconda3/lib/python3.6/site-packages/torch/utils/data/dataloader.py", line 307, in _process_next_batch
raise batch.exc_type(batch.exc_msg)
IndexError: Traceback (most recent call last):
File "/home/pf/anaconda3/lib/python3.6/site-packages/torch/utils/data/dataloader.py", line 57, in _worker_loop
samples = collate_fn([dataset[i] for i in batch_indices])
File "/home/pf/anaconda3/lib/python3.6/site-packages/torch/utils/data/dataloader.py", line 57, in
samples = collate_fn([dataset[i] for i in batch_indices])
File "/home/pf/instagan/data/unaligned_seg_dataset.py", line 71, in getitem
A_segs = self.read_segs(A_seg_path, seed)
File "/home/pf/instagan/data/unaligned_seg_dataset.py", line 45, in read_segs
segs.append(-torch.ones(segs[0].size()))
IndexError: list index out of range

It seem the occur int dataloader, but I still don't know how to solve it?
could you help me?