File "C:\vnstudio\lib\site-packages\rqdatac\services\basic.py", line 110, in _all_instruments_list
return [Instrument(i) for i in get_client().execute("all_instruments", market=market)]
TypeError: 'NoneType' object is not iterable
为什么[Instrument(i) for i in get_client().execute("all_instruments", market=market)]有时候可以获取到数据 list,但有时候获取到的却是 None