I can help you debug.
Note: I moved your post to a new thread since it’s a different error than the “access denied” SSL thread it was originally posted in.
This is not an error we have in our Unit Testing, so it may be an environment related issue. Can you clarify what version of WP, WC, and MyStyle are you using at the moment? Can you link me to your website so I can take a look?
FYI you shouldn’t need to “delete” mystyle if there is an issue with running it, you can simply disable the plugin in your WP Admin and it will not run in any way.
Do you have a dev site we could use to debug?
Are there any other plugins running that manipulate products in WooCommerce?