well if your looking for a crappy way to do it for now then you can always do something like this

Code:
  
myerrorscript {
  if (!$1) $error(myerrorscript,$script,$scriptline,Invalid Parameters)
  echo -a Complete
}
error { 
  echo -a * / $+ $$1 $+ : $$4 (line $$3 $+ , $remove($$2,$mircdir) $+ )
  halt
}

* /myerrorscript: Invalid Parameters (line 61, aliases.ini)