Link Contacts functionality is totally broken
If I link two contacts together, the result is supposed to be one contact with the contact details of both previous contacts. But with Contacts 42.0, the result is instead three contacts, one with the contact details of both contacts, and two with no contact details. If I then restart Contacts, I see the two original contacts as they were before I attempted to link them.
So we get: 2 contacts -> 3 contacts -> restart -> 2 contacts
But expected behavior is: 2 contacts -> 1 contact