Prevent uninit var warnings in Search/Biblio.pm

The logger messages in Search/Biblio.pm throw _many_ uninitialized
variable warnings. With a little care, we can prevent those warnings and
return our attention to more important log messages.

Signed-off-by: Dan Scott <dscott@laurentian.ca>
Signed-off-by: Ben Shum <bshum@biblio.org>