Bug 17380: Add some checks around Authorities::Types->find

Bug 17380: Add some checks around Authorities::Types->find

Resolves:
Use of uninitialized value $biblio_fields in scalar chop at authorities/detail.pl line 212.
Can't call method "authtypetext" on an undefined value at authorities/detail.pl line 216.
Can't call method "authtypecode" on an undefined value at authorities/detail.pl line 180.

NOTE: Some of these problems have actually been resolved now by bugs 18801
and 18811, but it is still better imo to have these checks.

Test plan:
[1] Verify unchanged behavior. Search for some authorities on authorities.pl
    and click on the details of a record.
[2] Open an authorities detail page and change the authid in the URL to a
    not existing number. Instead of an internal server error, you should see
    a message like "The authority record you requested does not exist".

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>