// [...]
if ($mollie_order->isPaid() || $mollie_order->isAuthorized()) {
    $trackingInfo = get_post_meta($order->id, '_wc_shipment_tracking_items', true);

    if (empty($trackingInfo)) {
        Mollie_WC_Plugin::getApiHelper()->getApiClient($test_mode)->orders->get($mollie_order_id)->shipAll();
        $order->add_order_note('Order successfully updated to shipped at Mollie, capture of funds underway.');
        Mollie_WC_Plugin::debug(__METHOD__ . ' - ' . $order_id . ' - Order successfully updated to shipped at Mollie, capture of funds underway.');
        return;
    }

    $trackingInfo = (object)$trackingInfo[0];
    $carrierName = !empty($trackingInfo->tracking_provider) ? $trackingInfo->tracking_provider : $trackingInfo->custom_tracking_provider;
    if (empty($carrierName)) {
        Mollie_WC_Plugin::getApiHelper()->getApiClient($test_mode)->orders->get($mollie_order_id)->shipAll();
        $order->add_order_note("Fulfillment doesn't seem to have a tracking tracking number. Fulfilling order without tracking info.");
        return;
    }

    if (empty($trackingInfo->tracking_number)) {
        Mollie_WC_Plugin::getApiHelper()->getApiClient($test_mode)->orders->get($mollie_order_id)->shipAll();
        $order->add_order_note("Fulfillment doesn't seem to have a tracking tracking number. Fulfilling order without tracking info.");
        return;
    }

    $trackingLink = !empty($trackingInfo->tracking_link) ? $trackingInfo->tracking_link : $trackingInfo->custom_tracking_link;
    if (empty($trackingLink)) {
        Mollie_WC_Plugin::getApiHelper()->getApiClient($test_mode)->orders->get($mollie_order_id)->shipAll();
        $order->add_order_note("Fulfillment doesn't seem to have a tracking link. Fulfilling order without tracking info.");
        return;
    }

    $tracking = [];
    $tracking['tracking'] = [
        'carrier' => $carrierName,
        'code' => $trackingInfo->tracking_number,
        'url' => $trackingLink
    ];
    Mollie_WC_Plugin::getApiHelper()->getApiClient($test_mode)->orders->get($mollie_order_id)->shipAll($tracking);
    // [...]
}