Bug 28581: (QA follow-up) Prevent code failure

Bug 28581: (QA follow-up) Prevent code failure

This patch prevents a fatal error when both $params->{from} and
$params->{borrowernumber} are undefined. We fallback to
KohaAdminEmailAddress before finally falling through to setting a
failure status for the message if that last fallback is not found.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>