Advanced Scripting - FileMaker Pro 13: The Missing Manual - page 889

Luckily, you can opt for more control over error handling if you want it. FileMaker gives you
three functions for finding and dealing with errors that may happen when scripts run.
The Set Error Capture Script Step
The Set Error Capture script step lets you turn on error capture . That way, instead of dis-
playing potentially confusing error messages to your database's users, FileMaker keeps track
of error information ( captures it) so you can pull it into your script and handle it there. Al-
though error capturing is a great feature, it's not part of FileMaker's normal behavior. You
have to activate it by adding the Set Error Capture step to your script, and choosing the
On option. At any time in the script, you can turn it back off again by using the step a second
time and switching the option off.
If a script turns error capture on and then uses the Perform Script step to run another script,
the second script also runs with error capture on. In other words, the error capture setting
sticks around as long as scripts call other scripts. But as soon as script execution stops for
good, FileMaker turns off error capture. Understanding this behavior helps you determine
when you need an Error Capture script step and when it would just be redundant. Fig-
ure 17-16 shows a script that turns on error capture before performing a find and then turns it
back off when it's done.
As discussed in the box below, you can just turn error capture on so that your script ignores
any and all errors—but that's not good script writing. The best way to use Set Error Cap-
ture is hand in hand with the Get(LastError) function, described next, to achieve error-
free results.