在运行cornernet的train文件时出现 TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

问题遇到的现象和发生背景

在运行cornernet的train文件时出现
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

问题相关代码，请勿粘贴截图

cfg_file = os.path.join(system_configs.config_dir, args.cfg_file + ".json")

运行结果及报错内容

Traceback (most recent call last):
File "/home/yu/下载/CornerNet-master/train.py", line 170, in
cfg_file = os.path.join(system_configs.config_dir, args.cfg_file + ".json")
TypeError: unsupported operand type(s) for +: 'NoneType' and 'str'

我想要达到的结果

求解答

改为 cfg_file = os.path.join(system_configs.config_dir, str (args.cfg_file) + ".json")之后，上个错误没了，但是出现以下错误：
File "/home/yu/下载/CornerNet-master/train.py", line 171, in
with open(cfg_file, "r") as f:
FileNotFoundError: [Errno 2] No such file or directory: './config/None.json'
求解决