DVID access problem with python client

HI,

When I start a client from python scripts (e.g example.py), I cannot add new layer through DVID url. However, the exact DVID url works fine if the client started with npm command. The traceback is :

Traceback (most recent call last):
File "C:\Users\ZJ\AppData\Local\Programs\Python\Python39\lib\site-packages\neuroglancer\sockjs_handler.py", line 51, in _on_changed
parsed_key = json.loads(key)
File "C:\Users\ZJ\AppData\Local\Programs\Python\Python39\lib\json\__init__.py", line 346, in loads
return _default_decoder.decode(s)
File "C:\Users\ZJ\AppData\Local\Programs\Python\Python39\lib\json\decoder.py", line 337, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "C:\Users\ZJ\AppData\Local\Programs\Python\Python39\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 42 (char 41)

Really appreciate any insights!