Bug 17692 - Can't add library EAN under Plack

Bug 17692 - Can't add library EAN under Plack

When adding a library ean under plack, there is an "internal server
error" when running Plack. Tested with Koha 16.11 release.

Test Plan:
1) Apply this patch
2) Enable Plack
3) Add, Edit and Delete a Library EAN

Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit ffcac846ad125534c0008291d53f094cfde6cc4b)
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>