if os.path.isdir(args.model_path): TypeError: _isdir: path should be string, bytes or os.PathLike, not NoneType

This error occurs because the variable `args.model_path` is `None`. The `os.path.isdir()` function expects a string, bytes, or `os.PathLike` object as its argument, but it cannot accept a `None` value.

To fix this error, you need to make sure that `args.model_path` is set to a valid string or `os.PathLike` object before passing it to `os.path.isdir()`. You can do this by checking the value of `args.model_path` before using it:

if args.model_path is not None and os.path.isdir(args.model_path):
    # do something with the model directory
else:
    # handle the case where args.model_path is None or not a valid directory path

This code first checks if `args.model_path` is not `None`, and then checks if it is a valid directory path using `os.path.isdir()`. If both conditions are true, you can proceed with using the model directory. Otherwise, you can handle the error or take some other action.