Issue #2933528 by nikita_tt, NickWilde: Attribute "class" should be an array

src/Plugin/views/exposed_form/BetterExposedFilters.php

@@ -1220,7 +1220,9 @@ Title Desc|Z -> A</pre> Leave the replacement text blank to remove an option alt
             '#title' => $form['#info']["filter-$label"]['label'] ?: '',
             '#description' => $form['#info']["filter-$label"]['description'] ?: '',
             // Needed to keep styling consistent with other exposed options.
-            '#attributes' => array('class' => 'form-item'),
+            '#attributes' => [
+              'class' => ['form-item'],
+            ],
             '#value' => NULL,
           ],
         ];