Error in refund event

[gjportegies]

The refund event falsely assumes the product on the order line_item still exists.
In our case the product does not exists in the store anymore resulting in the following error:

Error: Call to a member function get_id() on bool in /wp-content/plugins/taggrs-wordpress-plugin/includes/events/refund.php:12

The event should check if the product exists before using the object.

[BruceKristelijn]

Thank you for reporting this issue.

In the foreach loop I have added a empty check to skip empty / non existing products. I also noticed the category logging not working properly so I've added this aswell.

Feel free to test it on this branch to make sure it works for you aswell.