avoid croak on latest CVS version of MARC::Record

The semantics of MARC::Record->delete_field() changed
slightly in the latest CVS version of MARC::Record.
delete_field() will now croak if passed an undef
scalar, while the version of MARC::Record from CPAN
accepts that input.  Since some packages of MARC::Record
in the wild appear to be based on the CVS version, not
the CPAN version, added a check where needed to avoid
the croak.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>

diff --git a/C4/Biblio.pm b/C4/Biblio.pm
index 1f6be62..7d7e491 100755 (executable)
--- a/C4/Biblio.pm
+++ b/C4/Biblio.pm
@@ -2441,7 +2441,7 @@ sub _koha_marc_update_bib_ids {
 
         # drop old field and create new one...
         $old_field = $record->field($biblio_tag);
-        $record->delete_field($old_field);
+        $record->delete_field($old_field) if $old_field;
         $record->append_fields($new_field);
 
         # deal with biblioitemnumber
@@ -2454,7 +2454,7 @@ sub _koha_marc_update_bib_ids {
         }
         # drop old field and create new one...
         $old_field = $record->field($biblioitem_tag);
-        $record->delete_field($old_field);
+        $record->delete_field($old_field) if $old_field;
         $record->insert_fields_ordered($new_field);
 
     } else {
@@ -2467,7 +2467,7 @@ sub _koha_marc_update_bib_ids {
 
         # drop old field and create new one...
         my $old_field = $record->field($biblio_tag);
-        $record->delete_field($old_field);
+        $record->delete_field($old_field) if $old_field;
         $record->insert_fields_ordered($new_field);
     }
 }