Source source code not unique

This occurs when 2 events from the same network are within association distance, have both been deleted, and one is updated; because deleted products are ignored during the check. This occurs most commonly in indexers processing only a subset of product types (in this case origin), which is a common use case.

This fix (when event is deleted, consider deleted products) passes all the other tests, however it may be better to handle the deleted event case more carefully. Thoughts?