primitivus (chat): fixed a crash when page-up was pressed on room contacts list

frontends/src/primitivus/chat.py

@@ -157,6 +157,8 @@ class OccupantWidget(urwid.WidgetWrap):
         super(OccupantWidget, self).__init__(urwid.Text(markup))
 
     def __eq__(self, other):
+        if other is None:
+            return False
         return self.occupant_data.nick == other.occupant_data.nick
 
     def __lt__(self, other):