How to contour the error so to update query and trigger ask_bot?

[Takuzen]

AttributeError: 'str' object has no attribute 'payload'

I get this error and tried many ways (also with ChatGPT assistant), we could not clear this issue.

"""Welcome to Reflex! This file outlines the steps to create a basic app."""
from rxconfig import config

import reflex as rx
from gpt import VisionOSChatbot # Import VisionOSChatbot from gpt.py

# Create an instance of VisionOSChatbot
bot = VisionOSChatbot()

filename = f"{config.app_name}/{config.app_name}.py"

class State(rx.State):
    """The app state."""
    pass

class ChatState(rx.State):
    """Chat app state."""
    query: str = 'How to add a button to open full immersive space using swiftUI with visionOS?'
    response: str = ''

    def ask_bot(self):
        """Ask the bot."""
        if self.query:  # Only ask the bot if the user entered a query
            self.response = bot.ask(self.query, print_message=False)

    def update_query(self, event):
        """Update the query based on the event payload."""
        # The exact structure of the payload is not known, so this is a guess
        self.query = event.payload.get('value', '') 

def index() -> rx.Component:
    return rx.fragment(
        rx.color_mode_button(rx.color_mode_icon(), float="right"),
        rx.vstack(
            rx.box("visionOS Docs GPT", font_size="1em"),
            rx.text_area(
                placeholder="Q: Enter your query here",
                on_change=ChatState.update_query  # Update the query state variable when the textarea changes
            ),
            rx.text(f"A: {ChatState.response}", font_size="1em"),  # Display the bot's response
            rx.button(
                "Send",
                on_click=ChatState.ask_bot  # Trigger the ask_bot function when the button is clicked
            ),
            spacing="1.5em",
            font_size="1em",
            padding_top="10%",
        ),
    )

# Add state and page to the app.
app = rx.App(state=ChatState)
app.add_page(index)
app.compile()