Bug 35231: Resolve crash on unexisting patron in Auth

Bug 35231: Resolve crash on unexisting patron in Auth

Test plan:
Without this patch:
Logout from OPAC. Crash.
Try to login. Crash.

With this patch:
Enable login in tracking triggers. Clear lastseen.
Flush memcache.
Login. Check lastseen.
Logout.
Login.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Caroline Cyr La Rose <caroline.cyr-la-rose@inlibro.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>