ISTWCMS-5846: fixing undefined index on views admin page

uw_cfg_common.module

@@ -48,6 +48,7 @@ function uw_cfg_common_preprocess_form_element_label(&$variables) {
   // the id of the label contains edit-field-uw and has
   // either summary or position in the id.
   if (
+    isset($variables['element']['#id']) &&
     $variables['element']['#id'] !== 'edit-field-uw-blank-summary-value' &&
     str_contains($variables['element']['#id'], 'edit-field-uw-') &&
     (