我嘗試使用 RASA 來構(gòu)建一個(gè)示例機(jī)器人，但我收到了錯(cuò)誤消息，Bot loaded. Type a message and press enter (use '/stop' to exit):sadException in thread Thread-2:Traceback (most recent call last):  File "C:\python36\lib\threading.py", line 916, in _bootstrap_inner    self.run()  File "C:\python36\lib\threading.py", line 864, in run    self._target(*self._args, **self._kwargs)  File "C:\python36\lib\site-packages\rasa_core\channels\channel.py", line 291, in on_message_wrapper    on_new_message(message)  File "C:\python36\lib\site-packages\rasa_core\agent.py", line 316, in handle_message    return processor.handle_message(message)  File "C:\python36\lib\site-packages\rasa_core\processor.py", line 86, in handle_message    self._predict_and_execute_next_action(message, tracker)  File "C:\python36\lib\site-packages\rasa_core\processor.py", line 305, in _predict_and_execute_next_action    action, policy, confidence = self.predict_next_action(tracker)  File "C:\python36\lib\site-packages\rasa_core\processor.py", line 168, in predict_next_action    probabilities, policy = self._get_next_action_probabilities(tracker)  File "C:\python36\lib\site-packages\rasa_core\processor.py", line 478, in _get_next_action_probabilities    tracker, self.domain)  File "C:\python36\lib\site-packages\rasa_core\policies\ensemble.py", line 288, in probabilities_using_best_policy    if (result.index(max_confidence) ==AttributeError: 'NoneType' object has no attribute 'index'我用 ：PYTHON  3.6.0RASA CORE   0.12.0RASA NLU    0.13.0TENSORFLOW  1.10.0PROTOBUF    3.6.0有可能解決這個(gè)問題嗎？謝謝