LP#1511765 Fix error when checking in with zero-balance lost OU setting enabled

LP#1511765 Fix error when checking in with zero-balance lost OU setting enabled

Fixes an error generated when checking in Lost/Long Overdue/Lost and Paid
items with no associated circ when the org unit setting
circ.checkin.lost_zero_balance.do_not_change is set to TRUE

Items can attain this state from migration, or when the associated circ
has been aged.

Signed-off-by: Michele Morgan <mmorgan@noblenet.org>
Signed-off-by: Kyle Huckins <khuckins@catalyte.io>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>