Error in server.py

[Leonyxtested]

When starting the node and loading the interface it shows this error.

Task exception was never retrieved
future: <Task finished name='Task-7' coro=<Server.handle_connection() done, defined at C:\Users\de56002\Py\Proyectos\Block\server.py:30> exception=JSONDecodeError('Expecting value: line 1 column 1 (char 0)')>
Traceback (most recent call last):
File "C:\Users\de56002\Py\Proyectos\Block\server.py", line 40, in handle_connection
message = BaseSchema().loads(decoded_data) # <5>
File "C:\Users\de56002\Py\lib\site-packages\marshmallow\schema.py", line 756, in loads
data = self.opts.render_module.loads(json_data, **kwargs)
File "C:\Users\de56002\Py\lib\json_init_.py", line 346, in loads
return _default_decoder.decode(s)
File "C:\Users\de56002\Py\lib\json\decoder.py", line 337, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "C:\Users\de56002\Py\lib\json\decoder.py", line 355, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

As far as I could tell, it is receiving a String instead of being in JSON format.
Any way to fix it?