Why does my discord bot give the following error?

I don’t understand why it gives this error! It’s eating my head

 @client.event
    async def on_message(message):
        # Make sure bot doesn't get stuck in an infinite loop
        if message.author == client.user:
            return

        # Get data about the user
        username = str(message.author)
        user_message = str(message.content)
        channel = str(message.channel)

        # Debug printing
        print(f"{username} dice: '{user_message}' ({channel})")

        # If the user message contains a '?' in front of the text, it becomes a private message
        if user_message[0] == '?':
            user_message = user_message[1:]  # [1:] Removes the '?'
            await send_message(message, user_message, is_private=True)
        else:
            await send_message(message, user_message, is_private=False)

The only thing it does there is call a module called "send_message"

async def send_message(message, user_message, is_private):
     try:
         response = responses.handle_response(user_message)
         await message.author.send(response) if is_private else await message.channel.send(response)
     except Exception as e:
         print(e)

def handle_response(message) -> str:
     p__message = message.lower()
     if p__message == 'tell me something bana':
         return random.choice(bana_phrases)

400 Bad Request (error code: 50006): Cannot send an empty message

>Solution :

You should use a check to make sure handle_response function returns a string (it does not if the message is not tell me something bana):

async def send_message(message, user_message, is_private):
     try:
         response = responses.handle_response(user_message)
         if response:
              await message.author.send(response) if is_private else await message.channel.send(response)
     except Exception as e:
         print(e)