Fix [ bug #753 ] cashdesk : Error message when adding product to basket
https://doliforge.org/tracker/?func=detail&aid=753&group_id=144
http://www.dolibarr.fr/forum/526-autres-modules/39315-probleme-avec-point-de-vente
http://www.dolibarr.es/index.php/foro/6-icomo/2080-errores-con-tpv-y-tipos-de-iva
Merge pull request #718 from FHenry/3.3

Fix [ bug #753 ] cashdesk : Error message when adding product to basket