How to force failure?

How can I force a failure on a bad condition, so that "cobbler profile getks" fails with a traceback (and the actual kickstart fails, and validateks fails too)? For instance, I don't want to proceed if some variable is not set: #if $getVar('myvar','') != '' # ... do something with $myvar #else # Somehow throw an error to abort, e.g.: #error "The profile must define 'myvar'" #end if