prevent bots from banning mods

Author: majestrate

sogs/model.py

@@ -658,6 +658,10 @@ def ban_user(mod_user, room, ban_user):
             )
             return False
 
+        if mod_user is None and is_mod:
+            app.logger.warn("bots cannot ban moderators")
+            return False
+
         conn.execute(
             """
             INSERT INTO user_permission_overrides (room, user, banned, moderator, admin)