Problem with deploying the Flask app on Render

Question

I need to deploy my Telegram bot on the Render hosting, but there is an error in the server logs:enter image description here

In this application I used Flask, Telebot and waitress to create a server.

To run the application, I use command "python main.py".

Here is my code:

import os
import telebot
import DBService
from telebot import types
from flask import Flask, request, jsonify
from flask_cors import CORS
import json
from waitress import serve
from threading import Thread

app = Flask(__name__)
CORS(app) 
port = os.getenv('FLASK_PORT', '5000')


bot = telebot.TeleBot(TOKEN)
bot.set_webhook()




# some code




def run_flask():
    port = int(os.getenv('PORT', 5000))
    serve(app, host='0.0.0.0', port=port)

def run_bot():
    bot.polling(non_stop=True)


if __name__ == '__main__':
    # Parralel launch of Flask-app and Telegram bot
    flask_thread = Thread(target=run_flask)
    flask_thread.start()

    bot_thread = Thread(target=run_bot)
    bot_thread.start()

    flask_thread.join()
    bot_thread.join()

Could you tell what is wrong here?

I tried to use gunicorn instead of waitress, but nothing changed.