Fail gracefully, when an exception occurs during rendering of the example labels for label profiles

This fixes issue #671

Author: jbtronics

src/Controller/AdminPages/BaseAdminController.php

@@ -35,6 +35,7 @@
 use App\Entity\LabelSystem\LabelProfile;
 use App\Entity\Parameters\AbstractParameter;
 use App\Exceptions\AttachmentDownloadException;
+use App\Exceptions\TwigModeException;
 use App\Form\AdminPages\ImportType;
 use App\Form\AdminPages\MassCreationForm;
 use App\Repository\AbstractPartsContainingRepository;
@@ -53,6 +54,7 @@
 use Omines\DataTablesBundle\DataTableFactory;
 use Symfony\Bundle\FrameworkBundle\Controller\AbstractController;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
+use Symfony\Component\Form\FormError;
 use Symfony\Component\Form\FormInterface;
 use Symfony\Component\HttpFoundation\File\UploadedFile;
 use Symfony\Component\HttpFoundation\RedirectResponse;
@@ -211,7 +213,12 @@ protected function _edit(AbstractNamedDBElement $entity, Request $request, Entit
         //Show preview for LabelProfile if needed.
         if ($entity instanceof LabelProfile) {
             $example = $this->barcodeExampleGenerator->getElement($entity->getOptions()->getSupportedElement());
-            $pdf_data = $this->labelGenerator->generateLabel($entity->getOptions(), $example);
+            $pdf_data = null;
+            try {
+                $pdf_data = $this->labelGenerator->generateLabel($entity->getOptions(), $example);
+            } catch (TwigModeException $exception) {
+                $form->get('options')->get('lines')->addError(new FormError($exception->getMessage()));
+            }
         }
 
         /** @var AbstractPartsContainingRepository $repo */