Field formatter iterates over the entire list of product fields for each product displayed

Merge request created with proposed changes.

The formatter settings now show a helpful error message if it fails to build a list of options.

Thanks, merged! Trusting you on this, will address the test failures separately.

I'd be very surprised if this has any side effects since the parent field formatter still restricts this formatter to the variations field only. And the extra "check" only checked if there was product reference fields available. It never checked if one was actually configured. And in order to activate the formatter and save it requires a field to be referenced as my testing showed.

Automatically closed - issue fixed for 2 weeks with no activity.