TypeError: expected str, bytes or os.PathLike object, not NoneType

TypeError: expected str, bytes or os.PathLike object, not NoneType
if __name__ == '__main__':
    parser.add_argument("-f","--file",default="file")#接收这个-f参数
    args = parser.parse_args()
    print(args.file)
    patch_save_dir = os.path.join(args.save_dir, 'patches')
    mask_save_dir = os.path.join(args.save_dir, 'masks')
    stitch_save_dir = os.path.join(args.save_dir, 'stitches')

    if args.process_list:
        process_list = os.path.join(args.save_dir, args.process_list)

    else:
        process_list = None

    print('source: ', args.source)
    print('patch_save_dir: ', patch_save_dir)
    print('mask_save_dir: ', mask_save_dir)
    print('stitch_save_dir: ', stitch_save_dir)

######出现以下报错

TypeError                                 Traceback (most recent call last)
~\AppData\Local\Temp\ipykernel_7636\3173504493.py in 
    230         args = parser.parse_args()
    231         print(args.file)
--> 232         patch_save_dir = os.path.join(args.save_dir, 'patches')
    233         mask_save_dir = os.path.join(args.save_dir, 'masks')
    234         stitch_save_dir = os.path.join(args.save_dir, 'stitches')

D:\anaconda3\lib\ntpath.py in join(path, *paths)
     74 # Join two (or more) paths.
     75 def join(path, *paths):
---> 76     path = os.fspath(path)
     77     if isinstance(path, bytes):
     78         sep = b'\\'

TypeError: expected str, bytes or os.PathLike object, not NoneType

本来是这种错误，采取了上面的办法出现了这种报错

img

解决这个问题

os.path.join(args.save_dir, 'patches')报错了
args.save_dir的值是None