Add alert in user editor for method errors

Add an alert() in the user editor so that method errors are not
silent.

Without this, a method error (such as when saving a patron fails at
the db level) is silent. Better to at least inform the user that
something is amiss.

Signed-off-by: Jeff Godin <jgodin@tadl.org>
Signed-off-by: Mike Rylander <mrylander@gmail.com>