Bug 35335: Fix 500 on circulation history

Bug 35335: Fix 500 on circulation history

Koha::Patron->issuer is not covered by tests!

Test plan:
1. Set RecordStaffUserOnCheckout to "record"
2. Check an item out and in to a patron
3. Go to their circulation history
=> Without the patch you get an error
=> With this patch applied the table displayed correct. The "checkout by" column contains the name and the link to the librarian

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>