Versions

• OS: Arch Linux
• Gajim version: 1.1.95+x
• GTK version: 3.24.20
• Python-nbxmpp version: 0.9.94+x (latest master)

Steps to reproduce the problem

1. Go online with an account
2. Open "Modify Account ..." window (Alt+A)
3. Toggle switch next to the account name to disable the account

Expected behavior

Don't show the error message and disable account.

Actual behavior

29.04.2020 18:17:00 (W) nbxmpp.connection          (example.org) send() not possible in state: TCPState.DISCONNECTING
29.04.2020 18:17:00 (E) nbxmpp.dispatcher          (example.org) Handler exception:
Traceback (most recent call last):
  File "/home/user/python-nbxmpp/nbxmpp/dispatcher.py", line 454, in dispatch
    handler['func'](self._client, stanza, properties)
  File "/home/user/gajim/gajim/common/modules/muc.py", line 387, in _on_muc_user_presence
    contact = app.contacts.get_gc_contact(self._account,
  File "/home/user/gajim/gajim/common/contacts.py", line 508, in get_gc_contact
    return self._accounts[account].gc_contacts.get_gc_contact(room_jid, nick)
KeyError: 'example.org'

Note, example.org is the account name, as shown in the "Modify Account..." window.

Despite the error, the account has been disabled.