Bugfix: Adding error trapping for missing or invalid branch code

Bugfix: Adding error trapping for missing or invalid branch code

This patch adds code to trap, log, and return an intelligent message to the user
when a missing or invalid branch code is passed in. This condition can occur if
the user is logged in as the kohaadmin or the user has multiple instances of the staff
client open and has switched users in some instance.

Signed-off-by: Galen Charlton <gmcharlt@gmail.com>