Using Script Task On Business Process To Trigger an Exception

Hello, I'm using a script task based on signal record deleted that will trigger this exception. But somehow nothing showed not even a popup notification about the exception.

I tried creating a business process using the same script task that triggers an exception based on an object event process, and a notification popup was seen from the UI whenever the the condition was met.
 

The same way to throw the exception, yet different results. Why is that?
I need help and an explanation of this "throw new Exception..." on how it worked. If there is a work around to trigger this script task, I will be happy to discuss about it.