Truncate and Terminate PT compilation

System

The presentation templates here have a lot of embedded Perl that reads config files, etc. These things can encounter error conditions in which case I need to be able to give the user an error message (that can also be trapped in workflow to prevent deployment). I can't put all of the Perl at the top of the presentation template - I need to be able to generate the error message after some of the HTML in the PT has already been processed.

Is there some way to truncate the stream of data that would be written to the output file being generated so I can just output the error message and not the content that has already been processed in the PT and DCR? And how do I terminate processing of the PT after I have encountered the first error?