Perhaps a simple solution to some of the issues related to the unified editor always creating a new volume record would be to add a check that the new volume actually exists prior to trying to transfer the item to it.
Also worth noting here is that 1040686 is fixed in webby, so this issue may be as well.
Adding a link to a possibly related bug:
https:/ /bugs.launchpad .net/evergreen/ +bug/1253732
which is in turn related to:
https:/ /bugs.launchpad .net/evergreen/ +bug/1040686
Perhaps a simple solution to some of the issues related to the unified editor always creating a new volume record would be to add a check that the new volume actually exists prior to trying to transfer the item to it.
Also worth noting here is that 1040686 is fixed in webby, so this issue may be as well.