Bug 21203: ILS-DI - Make GetRecords handle non-existent records

Bug 21203: ILS-DI - Make GetRecords handle non-existent records

Caused by
  commit cb336e633bf7e0cb25051a8ed8157af8486a58d7
  Bug 18255: Koha::Biblio - Replace GetBiblioItemByBiblioNumber with Koha::Biblio->biblioitem

Can't call method "biblioitem" on an undefined value at /home/vagrant/kohaclone/C4/ILSDI/Services.pm line 212

Test plan:
- Enable ilsdi
- hit /cgi-bin/koha/ilsdi.pl?service=GetRecords&id=X
With X an existing biblionumber and a non existing one

Both requests must succeed

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit 88d3865168a83aa7e69999ab3336b238a2ed14ff)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>