tests: Clean up initialization of Error *err variables

Declaring a local Error *err without initializer looks suspicious.
Fuse the declaration with the initialization to avoid that.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191204093625.14836-5-armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
2 files changed