fix:fixed bug in old browsers

build/webpack.base.conf.js

@@ -49,7 +49,7 @@ module.exports = {
       {
         test: /\.js$/,
         loader: 'babel-loader',
-        include: [resolve('src'), resolve('test')]
+        include: [resolve('src'), resolve('test') ,resolve('node_modules/webpack-dev-server/client')]
       },
       {
         test: /\.svg$/,