catch error in SAIL interface

What kind of errors do you want to deal with ?
Is it validation errors or something else you are talking about ?

All errors can be raised by rules

AFAIK, there's no OOTB functionality to do this, but design errors (i.e. errors that came up in SAIL) are captured in design_error.csv

The file I mentioned (design_error.csv) is a system log file you can access if you have Admin level access.

As reginaldm377 stated, there is no OOTB functionality to do this on the sail side, but you can do error handing in the process model to send an email to a group/users to if a stored procedure fails.

Ideally your forms wouldn't error to begin with. There's a sort of catch 22 here which makes it at the very best difficult in Appian. To my knowledge there is no out of the box functionality to trigger an action when an error occurs, so to implement this you would need to identify the sections of your code that are causing the error, and display the desired message. But if you know where in the code the errors are, best practices state that you should fix the issue rather than displaying an error message. A custom plugin might be able to address this by detecting the error in Java and firing off actions based on what occurred, but that's probably more work than simply testing more rigorously to find issues before your users do.