You can only get that error on that line if the setting is set to yes. The only other thing I can suggest is to comment out the line causing the error untill I can fix it; unfortunately the fix requires rethinking the way I do it, so it'll take a bit of time.
To comment out the offending line, edit the global_start Activity Modification plugin, find
Code:
WWU002promoteUser($userinfo,0);
and replace it with
Code:
//WWU002promoteUser($userinfo,0);
I intend to post a release fixing this within the next week.