警告內容:
Warning: findDOMNode is deprecated in StrictMode. findDOMNode was passed an instance of Wave which is inside StrictMode. Instead, add a ref directly to the element you want to reference. Learn more about using refs safely here: https://fb.me/react-strict-mode-find-node
只要使用antd的組件就會有警告存在
警告原因：
是因為 react中的嚴格模式: `StrictMode`
解決辦法:
在`index.js`中掛載 App 的外面有這樣一個標簽
只要把這個標簽刪除掉就可以了
