Bug 23248: Avoid opac-ISBDdetail.pl breaking on invalid biblionumber

Bug 23248: Avoid opac-ISBDdetail.pl breaking on invalid biblionumber

This patch makes opac-ISBDdetail.pl redirect to a 404 page (as it
should) in the event of a bad biblionumber passed.

To test:
- Open your browser on a known record detail page (OPAC)
- Switch to the ISBD view
=> SUCCESS: It shows
- Alter the biblionumber on the URL into an obviously non-existent
biblionumber (e.g. very high value)
=> FAIL: Internal errors are shown
- Apply this patch
- Reload the bad biblionumber ISBD view
=> SUCCESS: Browser is redirected to the 404 page as it should
- Sign off :-=> FAIL: Internal errors are shown
- Apply this patch
- Reload the bad biblionumber ISBD view
=> SUCCESS: Browser is redirected to the 404 page as it should
- Sign off :-D

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
(cherry picked from commit c3f0732eb72dfb3c4c6000a8602424772bd46b61)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>