WordPress All-Import to ATUM Stock Management

When importing and creating/updating products in WooCommerce the fields used in and by ATUM Stock Management doesn't get updated.

On the stockmanagementlabs forum one user posted a suggestion to be added to functions.php:

add_action('pmxi_saved_post', 'post_saved', 10, 1);

function post_saved($id) {
    // get custom field
    $purchase_price = get_post_meta($id, '_atum_purchase_price', true);

    // Insert the field into the database
    if(isset($purchase_price)){
        $wpdb-update( 
            "{$wpdb-prefix}atum_product_data", 
            array( 
                'column1' = 'purchase_price', 
                'column2' = $purchase_price 
            ), 
            array(
                'product_id' = $id
            ),
            array( 
                '%s', 
                '%d' 
            ),
            array( '%d' )
        );
    }

    // Clean up unneeded custom field (OPTIONAL)
    delete_post_meta( $id, '_atum_purchase_price' )
}

This was later somewhat updated and revised by a developer of ATUM:

add_action('pmxi_saved_post', 'after_wpai_post_saved');

function after_wpai_post_saved($id) {
    // get custom field
    $purchase_price = get_post_meta($id, '_atum_purchase_price', true);

    // Insert the field into the database
    if( $purchase_price !== FALSE ){
        $wpdb-update( 
            "{$wpdb-prefix}atum_product_data", 
            array( 
                'purchase_price' = $purchase_price,               
            ), 
            array(
                'product_id' = $id
            ),
            array('%f'),
            array('%d')
        );
    }

    // Clean up unneeded custom field (OPTIONAL)
    delete_post_meta( $id, '_atum_purchase_price' )
}

This code however renders the white screen of death.

What I basically want to be able to do is import supplier ($supplier), supplier's SKU ($supplier_sku) and purchase price ($purchase_price) to ATUM while using WPAI to create/import products.