Do something like dont define a '/' in your ks. You'll get told you didn't, and when you hit 'Ok' you traceback.
This should be part of sanity checking we do of ks scripts.
We are in a bad place when this error occurs. The best I can do is have it next prompt the user that the system is being rebooted, thus avoided the traceback.
I'm going through Bugzilla closing some bugs that have been marked as Modified for some period of time. I believe that most of these issues have been fixed, so I'm resolving these bugs as Rawhide. If the bug you are seeing still exists, please reopen this report and mark it as Reopened.