Bug 24105: Fix error when running longoverdue.pl with --itemtypes

Bug 24105: Fix error when running longoverdue.pl with --itemtypes

To test:

Run Longoverdue.pl as koha-shell with both 1 and several --itemtypes specified
notice that it has an error
apply this patch
run longoverdue.pl as koha-shell with both 1 and several --itemtypes specified
notice there isn't an error anymore!

Signed-off-by: David Roberts <david.roberts@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit caba8dafb820448aca877c86682c28ff97953f3b)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>