I've got an error when I try to add some users to group chat
## Versions
- OS: Windows 7
- GTK+ Version: 3.22.30
- PyGObject Version: 3.28.1
- python-nbxmpp Version: 0.6.5
- Gajim Version: 1.0.2
## Traceback
```
Traceback (most recent call last):
File
"C:/msys64/home/appveyor/gajim/win/_build_root/mingw32/lib/python3.6/site-packages/gajim/dialogs.py",
line 2565, in _on_join_clicked
File
"C:/msys64/home/appveyor/gajim/win/_build_root/mingw32/lib/python3.6/site-packages/gajim/dialogs.py",
line 2593, in _add_bookmark
File
"C:/msys64/home/appveyor/gajim/win/_build_root/mingw32/lib/python3.6/site-packages/gajim/gui_interface.py",
line 2566, in add_gc_bookmark
TypeError: '>' not supported between instances of 'NoneType' and 'str'
```
## Steps to reproduce the problem
...