use jqXHR.fail() to check for failures
use jqXHR.fail() to check for failures

Signed-off-by: Artur Neumann <59bd0a3ff43b32849b319e645d4798d8a5d1e889@individual-it.net>
pixelipo/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,nextcloud/server,michaelletzgus/nextcloud-server,pixelipo/server,pixelipo/server,nextcloud/server,pixelipo/server,nextcloud/server,nextcloud/server,andreas-p/nextcloud-server,andreas-p/nextcloud-server,pixelipo/server,michaelletzgus/nextcloud-server,andreas-p/nextcloud-server,michaelletzgus/nextcloud-server,michaelletzgus/nextcloud-server