Bug 17709 - Article request broken - 'internal server error'

Bug 17709 - Article request broken - 'internal server error'

Article requsts from OPAC and from intranet are showing an 'internal
server error'. I am testing in 16.11 with Plack.

Test Plan:
1) Set circ rule to record only article requests
2) Attempt to place a request on a record with no items
3) Note the error
4) Apply this patch
5) You should now be able to place the request!

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>