label-studio-ml-backend: segment_anything_model reproduction error

1. after I follow segment_anything_model readme,I run python _wsgi.py -p 4243，get this

Traceback (most recent call last):
  File "/data/zqh/project/label-studio-ml-backend/label_studio_ml/examples/segment_anything_model/_wsgi.py", line 107, in <module>
    app = init_app(
          ^^^^^^^^^
TypeError: init_app() got an unexpected keyword argument 'model_dir'

1. then,i found init_app() define in api.py ,only model_class parameter,so i commented function init_app() 's parameters except for the model_class,then,code run sucess,but when i add model in Machine Larening,

    app = init_app(
        model_class=MyModel,
        # model_dir=os.environ.get('MODEL_DIR', args.model_dir),
        # redis_queue=os.environ.get('RQ_QUEUE_NAME', 'default'),
        # redis_host=os.environ.get('REDIS_HOST', 'localhost'),
        # redis_port=os.environ.get('REDIS_PORT', 6379),
        # **kwargs
    )

I get this

[2023-08-08 08:21:50,050] [INFO] [werkzeug::_log::187] 127.0.0.1 - - [08/Aug/2023 08:21:50] "GET /health HTTP/1.1" 200 -
[2023-08-08 08:21:50,069] [ERROR] [label_studio_ml.exceptions::exception_f::53] Traceback (most recent call last):
  File "/data/zqh/project/label-studio-ml-backend/label_studio_ml/exceptions.py", line 39, in exception_f
    return f(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^
  File "/data/zqh/project/label-studio-ml-backend/label_studio_ml/api.py", line 73, in _setup
    model = MODEL_CLASS(project_id, cache)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: MyModel.__init__() takes 1 positional argument but 3 were given

1. Then,I solved the problem by turning model = MODEL_CLASS(project_id, cache) into model = MODEL_CLASS(project_id=project_id, cache=cache)

4.next,i run code,I get

Traceback (most recent call last):
  File "/data/zqh/project/label-studio-ml-backend/label_studio_ml/exceptions.py", line 39, in exception_f
    return f(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^
  File "/data/zqh/project/label-studio-ml-backend/label_studio_ml/api.py", line 73, in _setup
    model = MODEL_CLASS(project_id=project_id, cache=cache)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/zqh/project/label-studio-ml-backend/label_studio_ml/examples/segment_anything_model/segment_anything_model.py", line 54, in __init__
    from_name, schema = list(self.parsed_label_config.items())[0]
                             ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/zqh/project/label-studio-ml-backend/label_studio_ml/model.py", line 58, in parsed_label_config
    return json.loads(self.get('parsed_label_config'))
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/anaconda3/envs/label-studio-ml/lib/python3.11/json/__init__.py", line 339, in loads
    raise TypeError(f'the JSON object must be str, bytes or bytearray, '
TypeError: the JSON object must be str, bytes or bytearray, not NoneType
[2023-08-08 09:01:40,045] [INFO] [werkzeug::_log::187] 127.0.0.1 - - [08/Aug/2023 09:01:40] "POST /setup HTTP/1.1" 500 -

the error code is below

    def parsed_label_config(self):
        return json.loads(self.get('parsed_label_config'))