"'generator' object has no attribute '__dict__'"#8

When I am calling GroupkFold.split() I am getting an error: error: undefined, exception: { type: { name: 'AttributeError', module: 'builtins' }, message: "'generator' object has no attribute '__dict__'", args: [ "'generator' object has no attribute '__dict__'" ], format: [ "AttributeError: 'generator' object has no attribute '__dict__'\n" ] traceback: { lineno: 111, strack: [ ' File "node_modules\\@fisch0920\\python-bridge\\node_python_bridge.py", line 114, in <module>\n' + " response = dict(type='exception', value=format_exception(t, e, tb))\n" ], format: [ ' File "..\\node_modules\\@fisch0920\\python-bridge\\node_python_bridge.py", line 111, in <module>\n' + " response = dict(type='success', value=json.dumps(value, separators=(',', ':'), cls=JavaScriptEncoder))\n", ' File "Programs\\Python\\Python310\\lib\\json\\__init__.py", line 238, in dumps\n' + ' **kw).encode(obj)\n', ' File "Programs\\Python\\Python310\\lib\\json\\encoder.py", line 199, in encode\n' + ' chunks = self.iterencode(o, _one_shot=True)\n', ' File "Python\\Python310\\lib\\json\\encoder.py", line 257, in iterencode\n' + ' return _iterencode(o, 0)\n', ' File "node_modules\\@fisch0920\\python-bridge\\node_python_bridge.py", line 81, in default\n' + ' return o.__dict__\n' ] }, I am confused why this error is triggered.