Error when atting user without @

[eryalito]

Traceback (most recent call last):
File "/usr/lib/python3.12/site-packages/telegram/ext/_application.py", line 1335, in process_update
await coroutine
File "/usr/lib/python3.12/site-packages/telegram/ext/_handlers/basehandler.py", line 157, in handle_update
return await self.callback(update, context)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/app/handlers/user/all.py", line 25, in run
users_str += '@' + user['username'] + ' '
~~~~^~~~~~~~~~~~~~~~~~
TypeError: can only concatenate str (not "NoneType") to str