Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: undefined. You likely forgot to export your component from the file it's defined in. Check the render method of `Add`.
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问题背景

使用React 15.6.1 + Webpack 3.6.0，导入一个组件

import  { Select,Option, OptGroup }  from '../../component/Tree';

结果控制台报错 ，错误信息信息如下所示：

发现这种错误其实很无奈，因为很隐蔽，没有指向具体的错误代码，不太容易定位到具体代码位置。 然而经过 Google 一番搜索，在 Stack Overflow 找到个说法。

解决办法

此处原因是因为 没有导出Option和OptGroup，这两个组件是在Select 组件下引出的。 要么直接 export const Option 和 export const OptGroup; 要么在Select导出： const { Option, OptGroup} = Select;;

上面的解决方法只是思路。遇到同样问题时，应该查找导入的类是否有问题，从而可以迅速的找到根源，同时也希望遇到问题的小伙伴能常去Stack Overflow摸索，各种各样的奇葩问题都能在这找到，就算找不到你想要的问题，也能有一些案例能够使你领悟。