No State or subdivision thereof may require the inspection or description in accordance with any standards of kind, class, quality, condition, or other characteristics of grain as a condition of shipment, or sale, of such grain in interstate or foreign commerce, or require any license for, or impose any other restrictions upon the performance of any official inspection or weighing function under this chapter by official inspection personnel. Otherwise nothing in this chapter shall invalidate any law or other provision of any State or subdivision thereof in the absence of a conflict with this chapter.