Warning: Undefined array key "sku" in C:\Inetpub\vhosts\tees.es\public\product-detail.php on line 4

Fatal error: Uncaught TypeError: ProductosModelo::validarSKU(): Argument #1 ($sku) must be of type string, null given, called in C:\Inetpub\vhosts\tees.es\public\product-detail.php on line 4 and defined in C:\Inetpub\vhosts\tees.es\public\class\ProductosModelo.php:534 Stack trace: #0 C:\Inetpub\vhosts\tees.es\public\product-detail.php(4): ProductosModelo::validarSKU() #1 {main} thrown in C:\Inetpub\vhosts\tees.es\public\class\ProductosModelo.php on line 534