Bug 28545: Noisy uninitialized warn at opac-MARCdetail.pl line 313

Bug 28545: Noisy uninitialized warn at opac-MARCdetail.pl line 313

Test plan:
You do not even need a NULL value in a authorised value controlled
item field, a zero in damaged or withdrawn is enough to trigger the
warnings. (Because only the 1 is linked to an authvalue.)

Check your plack-opac-error.log before and after applying this change.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Without the patch I had at least four warnings per item: withdrawn,
lost, damaged and notforloan.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>