我有一个WordPress网站：我想禁用其中一种付款方式（snapppay）对于属性vol具有3ml、5ml或10ml值的可变产品，如果只有这些产品在购物车中。例如，我的客户应该被允许任意数量的具有3ml、5ml、或10ml值与至少一个产品与任何不同的vol（不是3，5或10毫升）我尝试了这段代码，但我的网站停止工作：

function modify_available_payment_gateways($gateways) {
$flag = false;
$cart = WC()->cart;
$cart_num = count($cart->get_cart());
$dec_num = 0;
// Loop through cart items
foreach( $cart->get_cart() as $cart_item ) {
    if( $cart_item['variation_id'] > 0 ){
            // Loop through product attributes values set for the variation
            foreach( $cart_item['variation'] as $term_slug ){
                // comparing attribute term value with current attribute value
                if ($term_slug === '3ml' || $term_slug === '5ml' || $term_slug === '10ml') {
                    $dec_num = $dec_num + 1;
                }
            }
        }
    if ($cart_num === $dec_num){
        $flag = true;
    }
}

// When the flag is true
if ( $flag) {
    // Clear all other notices          
    wc_clear_notices();

    // Avoid checkout displaying an error notice
    wc_add_notice( __( 'My Error Message.', 'woocommerce' ), 'error' );
    
    // Optional: remove the payment method you want to hide
    unset($gateways['snapppay']);
}
return $gateways;
}
add_filter('woocommerce_available_payment_gateways', 'modify_available_payment_gateways');

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