jormun: check that viewargs is initialized before using it in get_used_coverage
jormun: check that viewargs is initialized before using it in get_used_coverage

kinnou02/navitia,pbougue/navitia,kinnou02/navitia,xlqian/navitia,CanalTP/navitia,pbougue/navitia,patochectp/navitia,CanalTP/navitia,patochectp/navitia,patochectp/navitia,antoine-de/navitia,kadhikari/navitia,antoine-de/navitia,CanalTP/navitia,CanalTP/navitia,pbougue/navitia,antoine-de/navitia,kinnou02/navitia,Tisseo/navitia,xlqian/navitia,kadhikari/navitia,xlqian/navitia,xlqian/navitia,pbougue/navitia,patochectp/navitia,CanalTP/navitia,antoine-de/navitia,kinnou02/navitia,Tisseo/navitia,Tisseo/navitia,kadhikari/navitia,xlqian/navitia,kadhikari/navitia,Tisseo/navitia,Tisseo/navitia