make helloasso form viewhelper error more explicit

ot_templating/Classes/ViewHelpers/HelloAsso/GetFormUrlByEventIdViewHelper.php

@@ -80,7 +80,7 @@ class GetFormUrlByEventIdViewHelper extends OtAbstractViewHelper {
             $form = $this->opentalentApiService->getJsonDecoded($uri);
         } catch (ApiRequestException $e) {
             OtLogger::error(sprintf('API Error: %s', $e->getMessage()));
-            return "<error>";
+            return "<error/><!--Error while getting the form data-->";
         }
 
         $variables = [$as => $form];