Custom Channel Error 'NoneType' object has no attribute 'startswith'

Rasa Open Source
1

Hi I am tryind to use the custom channel implementation from rasa docs getting below error while hitting from postman. In Rasa 1.10 Any help is appreciated @Juste

    [2021-03-11 16:39:36 +0530] [19968] [ERROR] Exception occurred while handling uri: 'http://localhost:5005/webhooks/myio/webhook'
    Traceback (most recent call last):
      File "\local\continuum\anaconda3\envs\rasax\lib\site-packages\sanic\app.py", line 976, in handle_request
        response = await response
      File "\custom_channel.py", line 50, in receive
        metadata=metadata,
      File "\local\continuum\anaconda3\envs\rasax\lib\site-packages\rasa\core\channels\channel.py", line 83, in handler
        await app.agent.handle_message(*args, **kwargs)
      File "local\continuum\anaconda3\envs\rasax\lib\site-packages\rasa\core\agent.py", line 486, in handle_message
        return await processor.handle_message(message)
      File "\local\continuum\anaconda3\envs\rasax\lib\site-packages\rasa\core\processor.py", line 94, in handle_message
        tracker = await self.log_message(message, should_save_tracker=False)
      File "\local\continuum\anaconda3\envs\rasax\lib\site-packages\rasa\core\processor.py", line 252, in log_message
        await self._handle_message_with_tracker(message, tracker)
      File "\local\continuum\anaconda3\envs\rasax\lib\site-packages\rasa\core\processor.py", line 486, in _handle_message_with_tracker
        parse_data = await self._parse_message(message, tracker)
      File "local\continuum\anaconda3\envs\rasax\lib\site-packages\rasa\core\processor.py", line 459, in _parse_message
        if message.text.startswith(INTENT_MESSAGE_PREFIX):
    AttributeError: 'NoneType' object has no attribute 'startswith'

credential.yml

custom_channel.MyIO:

custom_channel.py

class MyIO(InputChannel):
    def name(self) -> Text:
        """Name of your custom channel."""
        return "myio"

    def blueprint(
        self, on_new_message: Callable[[UserMessage], Awaitable[None]]
    ) -> Blueprint:

        custom_webhook = Blueprint(
            "custom_webhook_{}".format(type(self).__name__),
            inspect.getmodule(self).__name__,
        )

        @custom_webhook.route("/", methods=["GET"])
        async def health(request: Request) -> HTTPResponse:
            return response.json({"status": "ok"})

        @custom_webhook.route("/webhook", methods=["POST"])
        async def receive(request: Request) -> HTTPResponse:
            sender_id = request.json.get("sender") # method to get sender_id 
            text = request.json.get("text") # method to fetch text
            input_channel = self.name() # method to fetch input channel
            metadata = self.get_metadata(request) # method to get metadata

            collector = CollectingOutputChannel()

            await on_new_message(
                UserMessage(
                    text,
                    collector,
                    sender_id,
                    input_channel=input_channel,
                    metadata=metadata,
                )
            )

            return response.json(collector.messages)

        return custom_webhook