Bug 23248: (QA follow-up) Consolidate 404s

Merging two conditions: biblionumber is empty or biblionumber cannot be
found. This make the strange int($biblionumber) unneeded.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>

opac/opac-ISBDdetail.pl

@@ -59,11 +59,12 @@ use Koha::Biblios;
 
 my $query = CGI->new();
 my $biblionumber = $query->param('biblionumber');
-if ( !$biblionumber ) {
+my $biblio;
+$biblio = Koha::Biblios->find( $biblionumber, { prefetch => [ 'metadata', 'items' ] } ) if $biblionumber;
+if( !$biblio ) {
     print $query->redirect('/cgi-bin/koha/errors/404.pl');
     exit;
 }
-$biblionumber = int($biblionumber);
 
 #open template
 my ( $template, $loggedinuser, $cookie ) = get_template_and_user(
@@ -76,12 +77,6 @@ my ( $template, $loggedinuser, $cookie ) = get_template_and_user(
     }
 );
 
-my $biblio = Koha::Biblios->find( $biblionumber, { prefetch => [ 'metadata', 'items' ] } );
-unless ( $biblio ) {
-    print $query->redirect("/cgi-bin/koha/errors/404.pl");
-    exit;
-}
-
 my $patron = Koha::Patrons->find($loggedinuser);
 
 my $opachiddenitems_rules;