Thank you for this fix!

I applied the fix and ran the SQL update.

I am able to add credits now through the admin, but when I press "update", I get a blank page.
If I use the back arrow on the browser, the credit is added, and the customer gets an email.

The error log reads, in part: PHP Fatal error: require(): Failed opening required 'includes/modules/prod_cat_header_code.php'
This file does not exist and is not part of the store credit / rewards module.

Version 1.5.7b - upgraded from v1.5.2