Bug 19975: Fix search by tags at the OPAC

This bug has certainly be caused by
  commit 091d6c513b
    Bug 17843: Replace C4::Koha::getitemtypeinfo with Koha::ItemTypes

The reason is quite simple, in Koha::ItemType->translated_description
(called in opac-search.pl l.229) there is an eval to know if we have
access to the translated description of the item type, to avoid
retrieving it again.

The evaluation of $@ later in opac-search.pl is supposed to test the 2
eval made few lines before (a "normal" search, without tags), but
$@ contains the error message from the *last* eval command.
So we are raising an error that have been correctly handled in
Koha::ItemType.

Test plan:
At the OPAC, click Tag cloud, then click any of the tags

=> Without the patch you get
Koha::ItemType::get_column generated this error: DBIx::Class::Row::get_column(): No such column 'translated_description' on Koha::Schema::Result::Itemtype at /usr/share/koha/lib/Koha/Object.pm line 307

=> With the patch applied the page is correctly displayed

Signed-off-by: Claire Gravely <claire.gravely@bsz-bw.de>

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit fc172d3252)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>

opac/opac-search.pl

@@ -617,7 +617,7 @@ if ($tag) {
 }
 
 # use Data::Dumper; print STDERR "-" x 25, "\n", Dumper($results_hashref);
-if ($@ || $error) {
+if (not $tag and ( $@ || $error)) {
     $template->param(query_error => $error.$@);
     output_html_with_http_headers $cgi, $cookie, $template->output;
     exit;