feat: improved error handling and redirect on invalid session

src/Controller/Booking/Traits/BookingExceptionHandlerTrait.php

@@ -34,7 +34,7 @@ trait BookingExceptionHandlerTrait
         try {
             return $bookingService->getOrCreateBookingCreateDto($request);
         } catch (BookingSessionNotFoundException $e) {
-            $this->addFlash('error', 'Ihre Buchungssitzung ist abgelaufen. Bitte starten Sie eine neue Buchung.');
+            $this->addFlash('error', 'Deine Buchungssitzung ist abgelaufen. Bitte starte eine neue Buchung.');
 
             return $this->redirectToRoute('app_booking_create_error');
         } catch (TravelNotFoundException $e) {

src/Controller/Booking/Traits/ParticipantCardFlowTrait.php

@@ -8,6 +8,7 @@ use App\Form\BookingParticipantType;
 use App\Form\Model\BookingDto;
 use App\Form\Model\ParticipantEditDto;
 use Symfony\Component\Form\FormInterface;
+use Symfony\Component\HttpFoundation\RedirectResponse;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 
@@ -20,16 +21,18 @@ use Symfony\Component\HttpFoundation\Response;
 trait ParticipantCardFlowTrait
 {
     /**
-     * Load BookingDto from session or throw exception.
+     * Load BookingDto from session or return redirect to login.
      *
-     * @throws \RuntimeException When booking data not found in session
+     * Returns RedirectResponse when session data is missing (e.g., after cancel or session expiry).
      */
-    private function loadBookingDtoOrFail(Request $request, string $mode): BookingDto
+    private function loadBookingDtoOrRedirect(Request $request, string $mode): BookingDto|RedirectResponse
     {
         $bookingDto = $this->bookingService->getBookingDto($request, $mode);
 
         if (null === $bookingDto) {
-            throw new \RuntimeException(sprintf('Booking data not found in session for mode: %s', $mode));
+            $this->addFlash('info', 'Deine Sitzung ist abgelaufen. Bitte starte eine neue Buchung.');
+
+            return $this->redirectToRoute('app_login');
         }
 
         return $bookingDto;
@@ -183,4 +186,6 @@ trait ParticipantCardFlowTrait
     abstract private function render(string $view, array $parameters = [], ?Response $response = null): Response;
 
     abstract protected function addFlash(string $type, mixed $message): void;
+
+    abstract protected function redirectToRoute(string $route, array $parameters = [], int $status = 302): RedirectResponse;
 }