```js
function Editor({ data: { page } }: EditorProps) {
  if (page == null) throw Error('missing page data in editor')
  const [editorValue, setEditorValue] = useState(() => {
}
```

I believe this should be a valid case, because throw. 
} else if (
      node.parent.type === 'AssignmentPattern' &&
      node.parent.right === node &&
      !node.parent.computed
    ) {
      
      
      
      
      
      return node.parent.left;
    } else {
      return undefined;
    }
  } else {
    return undefined;
  }
}
/**
 * Convenience function for peeking the last item in a stack.
 */
function last(array) {
  return array[array.length - 1];
}