Use visitor functions' return values to check for failure. Eliminate
error_propagate() that are now unnecessary. Delete @err that are now
unused.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-41-armbru@redhat.com>