Could not response some error messages after update to the latest version

[sephyhe]

Hi there,

I recently updated the package version to the latest one and my previous version was on this commit 12f7a0aa277817b4861b29e2d71d44ecbd2289bf
Before, I can get some error messages like "Order does not contain FetchApp SKUs and is ignored". However, after updating, I could not get these error messages anymore and the response was just null. I was wondering if it is possible to have some more meaningful error messages in the response like before.

Thank you :)