Within Automattic\WooCommerce\Internal\Orders\CouponsController we reference the Exception type, but it is not fully qualified and there is no matching import statement. So, it is consequently expanded to:

Automattic\WooCommerce\Internal\Orders\Exception

That doesn't actually exist, so we likely intended to use a generic Exception. This change resolves that issue.

STEPS TO REPLICATE

1. Manually create or edit an order.
2. Try to apply a non-existent coupon code.
3. You should see an error informing you the coupon code does not exist:

4. Whereas, with current trunk code checked out, you will experience:
   • The above message will not appear: you will just see a spinner icon that keeps spinning indefinitely.
   • If you monitor the dev console, you will see the corresponding ajax request resulted in a 500 Internal Server Error.
   • In your error log, you may see an entry looking something like Uncaught Error: Class "Automattic\WooCommerce\Internal\Orders\Exception" not found in /.../src/Internal/Orders/CouponsController.php:80

FOR PR REVIEWER ONLY:

• I have reviewed that everything is sanitized/escaped appropriately for any SQL or XSS injection possibilities. I made sure Linting is not ignored or disabled.