Fatal error: Uncaught TypeError: in_array(): Argument #2 ($haystack) must be of type array, null given in /raid/home/aalst/classes/Pricing.php:218 Stack trace: #0 /raid/home/aalst/classes/Pricing.php(218): in_array('4924', NULL) #1 /raid/home/aalst/classes/Cart.php(184): Pricing->calculatePricing(Array) #2 /raid/home/aalst/cart/cart_lib.php(200): Cart->addToCart('4924', '0-309-56875-7', 'isbn', 1) #3 /raid/home/aalst/cart/cart_lib.php(86): addProducts(Array) #4 /raid/home/aalst/interface/basket.php(11): include('/raid/home/aals...') #5 /raid/home/aalst/cart/cart.php(4): include('/raid/home/aals...') #6 {main} thrown in /raid/home/aalst/classes/Pricing.php on line 218