Line 181:

throw new MigrateException(t("Asset for the article !path wasn't created as long as it doesn't have any associated title.",
        array('!path' => $row->lien)));

Error thrown:

Undefined property: stdClass::$lien File /modules/contrib/asset/includes/asset.migrate.inc, line 182(file: /modules/contrib/asset/includes/asset.migrate.inc, line 182)