Issue #3446612 by ptmkenny: test message form should show a useful error...

Issue #3446612 by ptmkenny: test message form should show a useful error message, not throw an exception

src/Form/FirebasePhpSendTestMessageForm.php

@@ -6,7 +6,6 @@ namespace Drupal\firebase_php\Form;
 
 use Drupal\Core\Form\FormBase;
 use Drupal\Core\Form\FormStateInterface;
-use Drupal\firebase_php\Exception\FirebasePhpException;
 use Drupal\firebase_php\FirebasePhpMessagingServiceInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
@@ -87,9 +86,15 @@ final class FirebasePhpSendTestMessageForm extends FormBase {
     try {
       $notification = $this->messagingService->createNotification($form_state->getValue('title'), $form_state->getValue('message'));
       $this->messagingService->sendMessageSingleDevice($form_state->getValue('device_token'), $notification);
+      $this->messenger()->addStatus($this->t('The test message has been sent to device token %token', [
+        '%token' => $form['device_token'],
+      ]));
     }
+    // @phpstan-ignore-next-line Exception is shown to admin, so no rethrowing.
     catch (\Exception $e) {
-      throw new FirebasePhpException($e->getMessage(), 0, $e);
+      $this->messenger()->addError($this->t('Failed to send the test message. Error: %error', [
+        '%error' => $e->getMessage(),
+      ]));
     }
   }