Bug 21248: Fix COinS carp in MARC details page on unknown record

Bug 21248: Fix COinS carp in MARC details page on unknown record

Looking up a nonexistent record in the MARC details -page causes
the COinS to carp. The fix is trivial, just move the COinS call
couple lines, after the record existence check.

TEST PLAN
---------
1) reset_all for kohadevbox
2) log in to staff client - admin/admin
3) search catalogue for green
4) tweak the top URL to have a bad biblionumber (eg. 9999)
5) cat /var/log/koha/kohadev/plack-err.log
   -- floody! with errors.
6) echo | sudo tee /var/log/koha/kohadev/plack-err.log
7) restart_all
8) repeat steps 2 through 5.
   -- just nice starting messages, not floody.
9) run koha qa test tools

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>