#3522889 Add Form Dumper Action, add warning missing symfony/var-dumper

src/Plugin/Action/FormDumper.php

@@ -56,6 +56,10 @@ class FormDumper extends FormFieldActionBase {
       if (function_exists('dump')) {
         dump($element);
       }
+      else {
+        $this->messenger()
+          ->addWarning($this->t('The symfony/var-dumper not found. Please install with command "composer require symfony/var-dumper".'));
+      }
     }
   }