Wrong behavior in bulk action filter

Version: 4.6.4
File: /includes/class-wcdn-writepanel.php
Method: my_bulk_action_handler

This method is a hooked method on ‘handle_bulk_actions-edit-shop_order’ filter, it should be always return the first parameter, which is $reidrect_to url.

For example.
In line 140, it checks if the action is in one of the plugin defined actions, if not, it should always return the original redirect_to url, not returning null. It will break
down another bulk actions hooked into the same filter from other plugins.

Please review it.
Regards.