TypeError: 'NoneType' object is not iterable

[KingCloser957]

使用python3的环境报这个错，有遇到过嘛？

Traceback (most recent call last):
File "Confuse.py", line 424, in
system_identifiers = DealSystemIdentifiers(system_dirs).parse_system_identifiers()
File "Confuse.py", line 225, in parse_system_identifiers
system_file_paths = ConfuseBiz.scan_path(self.system_file_dirs, None, ['h'])
File "Confuse.py", line 21, in scan_path
for input_dir in input_dirs:
TypeError: 'NoneType' object is not iterable