Issue #3502722 by grimreaper: Do not validate Layout Builder field when hidden

Closes #3502722

layout_builder_at.module

@@ -93,7 +93,7 @@ function layout_builder_at_form_entity_form_display_edit_form_alter(&$form, Form
 function layout_builder_at_validate_form_display($form, FormStateInterface $form_state) {
   $values = $form_state->getValues();
   if (isset($values['fields'][OverridesSectionStorage::FIELD_NAME])) {
-    if ($values['fields'][OverridesSectionStorage::FIELD_NAME]['type'] == 'layout_builder_widget') {
+    if ($values['fields'][OverridesSectionStorage::FIELD_NAME]['type'] == 'layout_builder_widget' && $values['fields'][OverridesSectionStorage::FIELD_NAME]['region'] != 'hidden') {
       $form_state->setErrorByName('fields][' . OverridesSectionStorage::FIELD_NAME, t('You can not select the Layout Builder Widget, please select a different widget.'));
     }
   }