Bug 9720 : uninitialized value warnings in circulation

Bug 9720 : uninitialized value warnings in circulation

This patch corrects several uninitialized value errors.

Test plan:
- Go to check out page
- Check that issues and old issues are in different tables
- Check that author is diplayed if exists
- Check that patron address is displayed if exists
- Perform a checkout

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>