This patch adds tests for the case in which there's no object identified
by the supplied $id. It should return undef.
Sponsored-by: Virginia Polytechnic Institute and State University Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io> Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com> Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com> Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>