Bug 25913: Prevent get_coins to crash if record does not have title

Bug 25913: Prevent get_coins to crash if record does not have title

If a bibliographic record does not have a title, get_coins will crash
with
Can't call method "as_string" on an undefined value at /kohadevbox/koha/Koha/Biblio.pm line 645
Koha::Biblio::get_coins('Koha::Biblio=HASH(0x5558f91bb740)') called at /kohadevbox/koha/catalogue/ISBDdetail.pl line 144

We can handle that situation easily by checking the existence of the
title field.

Test plan:
1. Create a record without 245
2. Enable COinSinOpac
4. Go to the ISBD detail view
=> It must not fail with this patch applied

Signed-off-by: Heather Hernandez <heather_hernandez@nps.gov>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@helsinki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>