How to fail a form

Product: PowerShell Universal
Version: 2.4.0 Sept 24 Nightly
System Powershell 5.1 Environment

How can I intentionally fail a script attached to a form (in a page) so that it shows an informative error to the user in the failure text? Ex: Failed: Invalid computer name or somesuch.

The nightly build should actually do this now. If you throw an error and set the error action to stop for the script, the thrown error will be displayed.