Process Model stack error

I want to be able to stop a process model. What I currently do: I exit with failure in the working step and in the error transition step, I branch on the error message. If the error message is STOP, I get the process instance into status Completed by calling pub.prt.admin:changeProcessStatus and setting the action parameter to DONE.

In order for non technicians to get something understandable out from WmMonitor I would like to have a process instance in status Completed without the load of stack-trace and operations.
How to get rid of the stack trace?

By the way, we are using IS 6.0.1 SP2, Modeler SP1