Issue #3501430 by just_like_good_vibes: Extra slots level in data state

Closes #3501430

src/Element/ComponentForm.php

@@ -270,9 +270,7 @@ class ComponentForm extends ComponentFormBase {
       '#tag_filter' => $element['#tag_filter'],
       '#ajax_url' => $element['#ajax_url'] ?? NULL,
       '#access' => $element['#render_slots'] ?? TRUE,
-      '#default_value' => [
-        'slots' => $element['#default_value']['slots'] ?? [],
-      ],
+      '#default_value' => $element['#default_value']['slots'] ?? NULL,
     ];
   }