to catch error events you need to declare error boundary event with coresponding error code. If you use 5.2 then error boundary event can be attached to only sub processes from 5.3 you can attach boundary events on tasks as well. Once error event is caught you can start alternative path in the process. Take a look at the example here
Thanks for the reply, I will try to see if i can get this to work with the example.
Update: I was able to get it to work, i think the issue was how to make the signal event node a boundary event. I didn't realize that there was metadata that defined that (in this case having the AttachedTo).
So adding the AttachedTo and ErrorEvent allowed it to work as well as having the event type set to be "Error-_22-MyError" where _22 is the subprocess id and MyError matches the Exception Handler for the subprocess.