Value error in get_role_iter when enabling 'Sort contacts by status in group chats'

Versions

• OS: Ubuntu 18.10
• GTK+ Version: 3.24.4
• PyGObject Version: 3.30.1
• python-nbxmpp Version: 0.6.10
• Gajim Version: 1.1.2+366b3df2

Traceback

Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/gajim/gtk/preferences.py", line 552, in on_sort_by_show_in_muc_checkbutton_toggled
    ctrl.draw_roster()
  File "/usr/lib/python3/dist-packages/gajim/groupchat_control.py", line 1719, in draw_roster
    gc_contact.affiliation, gc_contact.status, gc_contact.jid)
  File "/usr/lib/python3/dist-packages/gajim/groupchat_control.py", line 2105, in add_contact_to_roster
    role_iter = self.get_role_iter(role)
  File "/usr/lib/python3/dist-packages/gajim/groupchat_control.py", line 2150, in get_role_iter
    return self.model.get_iter(path)
  File "/usr/lib/python3/dist-packages/gi/overrides/Gtk.py", line 866, in get_iter
    raise ValueError("invalid tree path '%s'" % path)
ValueError: invalid tree path '1'

Steps to reproduce the problem

In preferences dialog: enable 'sort contacts by status in group chats'