Warning: Parameter 1 to Drupal\field_group\FormatterHelper::formProcess() expected to be a reference, value given in Drupal\Core\Render\Renderer->doTrustedCallback() (line 101 of core/lib/Drupal/Core/Security/DoTrustedCallbackTrait.php).
Drupal\Core\Render\Renderer->doTrustedCallback(Array, Array, 'Render #pre_render callbacks must be methods of a class that implements \Drupal\Core\Security\TrustedCallbackInterface or be an anonymous function. The callback was %s. See https://www.drupal.org/node/2966725', 'exception', 'Drupal\Core\Render\Element\RenderCallbackInterface') (Line: 781)