Group chat roster throws KeyError: 'none' in _tree_compare_iters

Versions

• OS: Windows
• GTK Version: 3.24.18
• PyGObject Version: 3.36.0
• GLib Version : 2.64.1
• python-nbxmpp Version: 0.9.95
• Gajim Version: 1.1.99

Traceback

Traceback (most recent call last):
  File "C:/msys64/home/appveyor/gajim/win/_build_root/mingw64/lib/python3.8/site-packages/gajim/gtk/groupchat_roster.py", line 356, in _tree_compare_iters
KeyError: 'none'

I have done nothing. ...