Ant-design: TypeError：当值为null的渲染Button时，无法读取null的属性“ type”。

环境（必填）

• antd版本：2.8.2
• 操作系统及其版本：macOS 10.11.6
• 浏览器及其版本：Chrome 57

你做了什么？ 请提供步骤以重现您的问题。

<Button>{null}🙃</Button>

您期望什么？

正确呈现按钮（ <button>🙃</button> ）。

发生什么事？

insertSpace方法执行快递null.type 。
导致类型错误：

Uncaught TypeError: Cannot read property 'type' of null
    at insertSpace (unpkg.com/[email protected]/dist/antd-with-locales.js:88201)
    at mapSingleChildIntoContext (unpkg.com/[email protected]/dist/react.js:371)
    at traverseAllChildrenImpl (unpkg.com/[email protected]/dist/react.js:3390)
    at traverseAllChildrenImpl (unpkg.com/[email protected]/dist/react.js:3406)
    at traverseAllChildren (unpkg.com/[email protected]/dist/react.js:3485)
    at mapIntoWithKeyPrefixInternal (unpkg.com/[email protected]/dist/react.js:391)
    at Object.mapChildren [as map] (unpkg.com/[email protected]/dist/react.js:413)
    at Button.render (unpkg.com/[email protected]/dist/antd-with-locales.js:88303)
    at unpkg.com/[email protected]/dist/react-dom.js:5250
    at measureLifeCyclePerf (unpkg.com/[email protected]/dist/react-dom.js:4529)

可复制的在线演示

http://codepen.io/blade254353074/pen/wJXgrL