How do you throw an error from a Notebook so a Data Factory pipeline knows to stop running?

Thanks for the reply, frithjof_v. The challenge there is I'd then need to add logic in the pipeline to evaluate whether or not the exit value output indicates an error.

The solution I found (which I found somewhere on the internet that I don't recall) is to use raise Exception("Error message here"). Here's a modified version of the code block; the vars are just fake examples of operations I am performing:

if var == None:
  raise Exception("No match found.")
else: 
    var2 = var

This sends the exception back as an error to the pipeline so the Notebook activity actually fails, which is handy.