Telegram bot code gives an error what are they doing?

Question

Python

here is the code

import telebot
import service
import requests
import re
from correct import InstagramLinksCorrect
from bs4 import BeautifulSoup
import logging

class ParseHashes:
    patterns=service.OldPatterns()
    code_with_hash_pattern=re.compile(r'"code"[ ]*:[ ]*"{}"'.format(patterns.image_hash_pattern))
    hash_pattern=re.compile(patterns.image_hash_pattern)
    def get_hashes(self,page_source):
        temp_result=re.findall(self.code_with_hash_pattern,page_source)
        hashes = []
        for code_with_hash in temp_result:
            temp=re.findall(self.hash_pattern,code_with_hash)
            code,hash=temp[0],temp[1]
            hashes.append(hash)
        return tuple(hashes)

def get_source_by_link(link):
    links_tester=InstagramLinksCorrect()
    if not links_tester.ImageLinkIsValid(link):
        return None
    page_source=requests.get(link).text
    soup=BeautifulSoup(page_source,'html.parser')
    for meta_tag in soup.find_all('meta'):
        if meta_tag.get('property', None) == 'og:image':
            return meta_tag.get("content", None)


def get_tuple_of_sources_by_account(link):
    """Класс выдает кортеж ссылок по ссылке на профиль."""
    links_tester = InstagramLinksCorrect()
    if not links_tester.AccountLinkIsValid(link):
        return None

    page_source = requests.get(link).text
    parser=ParseHashes()
    hashes=parser.get_hashes(page_source)

    sources=[]
    for hash in hashes:
        source=get_source_by_link('http://instagram.com/p/{}'.format(hash))
        sources.append(source)
    return tuple(sources)

def get_links_from_message(message):
    patterns=service.NewPatterns()
    acc_reg=re.compile(patterns.account_link_pattern)
    im_reg=re.compile(patterns.image_link_pattern)
    account_links=re.findall(acc_reg,message)
    image_links=re.findall(im_reg,message)
    return account_links,image_links

bot=telebot.TeleBot(token=service.telegram_token)



@bot.message_handler(commands=['start', 'help'])
def handle_start_help(message):
    bot.send_message(message.chat.id, service.welcome_message)



@bot.message_handler(content_types=['text'])
def handle_message(message):
    account_links,image_links=get_links_from_message(message.text)
    sources=[]
    for account_link in account_links:
        sources_by_account_link=get_tuple_of_sources_by_account(account_link)
        sources.extend(sources_by_account_link)
    for image_link in image_links:
        source=get_source_by_link(image_link)
        sources.append(source)
    for i in range(len(sources)):
        link=sources[i]
        bot.send_message(message.chat.id,'<a href="{}">{}</a>'.format(link,i),parse_mode='HTML')

logger=telebot.logger
telebot.logger.setLevel(logging.DEBUG)
bot.polling(none_stop=True)

here is the error
2021-11-16 03:40:23,787 (util.py:93 WorkerThread2) DEBUG - TeleBot: "TypeError occurred, args=("'NoneType' object is not iterable",)
Traceback (most recent call last):
File "C:\Users\ArtlorD)\AppData\Local\Programs\Python\Python38\lib\site-packages\telebot\util.py", line 87, in run
task(*args, **kwargs)
File "c :\Users\ArtlorD)\Desktop\instagram-downloader-bot-master\main.py", line 73, in handle_message
sources.extend(sources_by_account_link)
TypeError: 'NoneType' object is not iterable
"
Traceback (most recent call last) :
File "c:\Users\ArtlorD)\Desktop\instagram-downloader-bot-master\main.py", line 83, in
bot.polling(none_stop=True)
File "C:\Users\ArtlorD)\AppData\Local\Programs\Python\Python38\lib\site-packages\telebot\__init__.py", line 660, in polling
self.__threaded_polling(non_stop, interval, timeout, long_polling_timeout, allowed_updates)
File "C:\Users\ArtlorD)\AppData\Local\Programs\Python\Python38\lib\site-packages\telebot\__init__.py", line 722, in __threaded_polling
raise e
File "C:\Users\ArtlorD )\AppData\Local\Programs\Python\Python38\lib\site-packages\telebot\__init__.py", line 682, in __threaded_polling
self.worker_pool.raise_exceptions()
File "C:\Users\ArtlorD)\AppData\Local \Programs\Python\Python38\lib\site-packages\telebot\util.py", line 135, in raise_exceptions
raise self.exception_info
File "C:\Users\ArtlorD)\AppData\Local\Programs\Python\Python38\lib\site-packages\telebot\util.py", line 87, in run
task(*args, **kwargs)
File "c :\Users\ArtlorD)\Desktop\instagram-downloader-bot-master\main.py", line 73, in handle_message
sources.extend(sources_by_account_link)
TypeError: 'NoneType' object is not iterable
what do you do?