Bug 25248: (bug 23463 follow-up) Adjust second occurrence

Same as the precedent patch for a single item deletion (vs delete all
items)
Item is returned if deletion  successful, not 1

Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

cataloguing/additem.pl

@@ -675,7 +675,7 @@ if ($op eq "additem") {
     # check that there is no issue on this item before deletion.
     my $item = Koha::Items->find($itemnumber);
     $error = $item->safe_delete;
-    if($error ne '1'){
+    if(ref($error) eq 'Koha::Item'){
         print $input->redirect("additem.pl?biblionumber=$biblionumber&frameworkcode=$frameworkcode&searchid=$searchid");
     }else{
         push @errors,$error;