NoneType'

[wangning7149]

你好！，运行代码 出现以下错误，请问是什么原因呢？

Traceback (most recent call last):
File "labelme2coco.py", line 162, in
labelme2coco(labelme_json,'train.json')
File "labelme2coco.py", line 34, in init
self.save_json()
File "labelme2coco.py", line 142, in save_json
self.data_transfer()
File "labelme2coco.py", line 42, in data_transfer
self.images.append(self.image(data,num,file_name))
File "labelme2coco.py", line 54, in image
img = img_b64_to_arr(data['imageData'])
File "/home/zhixing/mmdetection-2.1.0/image.py", line 12, in img_b64_to_arr
f.write(base64.b64decode(img_b64))
File "/home/zhixing/anaconda3/lib/python3.7/base64.py", line 80, in b64decode
s = _bytes_from_decode_data(s)
File "/home/zhixing/anaconda3/lib/python3.7/base64.py", line 46, in _bytes_from_decode_data
"string, not %r" % s.class.name) from None
TypeError: argument should be a bytes-like object or ASCII string, not 'NoneType'