报错内容如下：

2020-06-06 12:58:25,180-INFO: Total number of images: 4000, inference time: 12.819232320486554 fps.
loading annotations into memory...
Traceback (most recent call last):
File "PaddleDetection/tools/eval.py", line 190, in
main()
File "PaddleDetection/tools/eval.py", line 173, in main
dataset=dataset)
File "/home/aistudio/PaddleDetection/ppdet/utils/eval_utils.py", line 209, in eval_results
is_bbox_normalized=is_bbox_normalized)
File "/home/aistudio/PaddleDetection/ppdet/utils/coco_eval.py", line 74, in bbox_eval
coco_gt = COCO(anno_file)
File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/site-packages/pycocotools/coco.py", line 84, in __init__
dataset = json.load(open(annotation_file, 'r'))
File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/json/__init__.py", line 296, in load
parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/json/__init__.py", line 348, in loads
return _default_decoder.decode(s)
File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/json/decoder.py", line 337, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/opt/conda/envs/python35-paddle120-env/lib/python3.7/json/decoder.py", line 355, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)