webpack-dev-server Nodejs API中运行inline模式 失败

Question

webpack-dev-server Nodejs API中运行inline模式 失败:
打开http://localhost:8091/， 显示404

文件结构如下：

-build
--app.js
--app.css
-index.html

webpack.config.js 如下：

entry: {
    app: [
      './src/Main'
    ]
  },
  output: {
    publicPath : '/assets/',
    path : __dirname + '/build',
    filename: 'app.js'
  },

server.js 如下：

var config = require("./webpack.config.js");
var webpack = require('webpack');
var WebpackDevServer = require('webpack-dev-server');

config.entry.app.unshift("webpack-dev-server/client?http://localhost:8091/");

var compiler = webpack(config);
var server = new WebpackDevServer(compiler, {
  contentBase:'build/',
  publicPath: config.output.publicPath
});
server.listen(8091);

命令行代码如下：

    "dev-hot":"node server-devServer-hot.js"

现在发现