Store the volume of an order in the DB

Hi everyone, hope you are all fine.
I am not really sure of wat i am doing, but in a nutshell i want to calculate the volume of an order and sore it in the DB. I am working with the woocommerce Rest API and when i retrive the orgder i dont have the 3 measur of the item bought so i tought to do as i have already don with the total weight sored as a meta data in the db and then retreived trough the API.

i ma doing like this but it breaks me the closing of the order. I receive the message Internal server Error. Can you help me to adjust it?

// Store volume in the database
add_action('woocommerce_checkout_update_order_meta', 'woo_add_cart_volume');

function woo_add_cart_volume( $order_id ) {
    global $woocommerce;

     foreach( $order->get_items() as $item ){
        $product_volume = (float) get_post_meta( $item->get_product_id(), '_item_volume', true );
        $total_volume  += $product_volume * $item->get_quantity();
    }
    
    update_post_meta( $order_id, '_item_volume', $total_volume );
}

Thank you