Undefined attribute with telegram API

Question

My apologies. This is the first bit of code I've written. Spent all day trying to find a way to sort it and this is my last resort. When someone forwards a message with a username I've defined - the bot sends a message back saying it's a real user. When someone forwards a message with no username, the bot sends a message back saying it's probably a scammer... but when someone forwards a message from someone with no username and who's disallowed message forwarding in their Telegram settings, I get an undefined attribute error.

AttributeError: 'NoneType' object has no attribute 'username'

here is my code

`

#!/usr/bin/python3

from telegram.ext.updater import Updater
from telegram.update import Update
from telegram.ext.callbackcontext import CallbackContext
from telegram.ext.commandhandler import CommandHandler
from telegram.ext.messagehandler import MessageHandler
from telegram.ext.filters import Filters

updater = Updater("My Token", use_context=True)

def start(update: Update, context: CallbackContext):
    update.message.reply_text(
        "Hi. I'm a bot that sniffs out this softwares scammers so you don't get exploited. Simply forward a message from the scammer to me "
        "and I'll tell you if it's the real support or not.")

def usercheck(update: Update, context: CallbackContext):
     if update.effective_message.forward_from.username == "admin1":
        update.effective_message.reply_text("✅This message was sent from the real admin1, an authorised reseller from this group")
     elif update.effective_message.forward_from.username == "dev1":
          update.effective_message.reply_text("✅This message was sent from the real dev1, an authorised developer of group")
     elif update.effective_message.forward_from.username == None:
          update.effective_message.reply_text("🚨🚨🚨🚨🚨 If this user says they're from Gunbot support - they are trying to scam you. "
           "Please report them and stop talking to them immediately. 🚨🚨🚨🚨🚨") #works but only if the user has no privacy settings
     else:
          update.effective_message.reply_text("🚨🚨🚨🚨🚨 If this user says they're from My softwares support - they are trying to scam you. "
           "Please report them and stop talking to them immediately. 🚨🚨🚨🚨🚨") #would have thought it works if the user hides their privacy settings but it doesn't 

updater.dispatcher.add_handler(CommandHandler("start", start))
updater.dispatcher.add_handler(MessageHandler(Filters.forwarded, usercheck))
updater.start_polling()
updater.idle()

`

Answer 1

From the telegram docs, forward_from is optional, so it could be None. You should verify that update.effective_message.forward_from is not None before accessing effective_message.forward_from.username.

def usercheck(update: Update, context: CallbackContext):
    if update.effective_message.forward_from is not None:
        if update.effective_message.forward_from.username == "admin1":
        # ...
    else:
        # do something else