diff --git a/src/Controller/InvoiceServiceController.php b/src/Controller/InvoiceServiceController.php
index 94e201a..c623812 100644
--- a/src/Controller/InvoiceServiceController.php
+++ b/src/Controller/InvoiceServiceController.php
@@ -183,7 +183,7 @@ public function getReservationsInPeriodAction(ManagerRegistry $doctrine, Request
     {
         $em = $doctrine->getManager();
         $reservations = [];
-        $newInvoiceInformationArray = $requestStack->getSession()->get('invoiceInCreation');
+        $newInvoiceInformationArray = $requestStack->getSession()->get('invoiceInCreation', []);
 
         $potentialReservations = $em->getRepository(
             Reservation::class
@@ -209,7 +209,6 @@ public function getReservationsForCustomerAction(ManagerRegistry $doctrine, Requ
     {
         $em = $doctrine->getManager();
         $reservations = [];
-        $newInvoiceInformationArray = $requestStack->getSession()->get('invoiceInCreation');
 
         $customer = $em->getRepository(Customer::class)->findOneByLastname(
             $request->request->get('lastname')
@@ -220,7 +219,7 @@ public function getReservationsForCustomerAction(ManagerRegistry $doctrine, Requ
                 Reservation::class
             )->loadReservationsWithoutInvoiceForCustomer($customer);
 
-            $newInvoiceInformationArray = $requestStack->getSession()->get('invoiceInCreation');
+            $newInvoiceInformationArray = $requestStack->getSession()->get('invoiceInCreation', []);
 
             foreach ($potentialReservations as $reservation) {
                 if (!in_array($reservation->getId(), $newInvoiceInformationArray)) {
@@ -247,6 +246,7 @@ public function selectReservationAction(ManagerRegistry $doctrine, InvoiceServic
         }
 
         if (null != $request->request->get('reservationid')) {
+            $newInvoiceInformationArray = $requestStack->getSession()->get('invoiceInCreation', []);
             $newInvoiceInformationArray[] = $request->request->get('reservationid');
             $requestStack->getSession()->set('invoiceInCreation', $newInvoiceInformationArray);
         }
diff --git a/src/Service/ReservationService.php b/src/Service/ReservationService.php
index ad58085..fd7846e 100644
--- a/src/Service/ReservationService.php
+++ b/src/Service/ReservationService.php
@@ -19,6 +19,7 @@
 use App\Entity\Reservation;
 use App\Entity\ReservationStatus;
 use App\Entity\Template;
+use App\Entity\CustomerAddresses;
 use App\Interfaces\ITemplateRenderer;
 use Doctrine\Common\Collections\ArrayCollection;
 use Doctrine\Common\Collections\Collection;
@@ -368,7 +369,7 @@ public function getRenderParams(Template $template, mixed $param)
         // params need to be an array containing a list of Reservation Objects
         $params = [
                 'reservation1' => $param[0],
-                'address' => (0 == count($param[0]->getBooker()->getCustomerAddresses()) ? null : $param[0]->getBooker()->getCustomerAddresses()[0]),
+                'address' => (0 == count($param[0]->getBooker()->getCustomerAddresses()) ? new CustomerAddresses() : $param[0]->getBooker()->getCustomerAddresses()[0]),
                 'reservations' => $param,
             ];
         $prices = $this->getTotalPricesForTemplate($param);