有关webpack自动编译配置问题

index.html
<!DOCTYPE html>
<html lang="en">
<head>
    <title>Getting Started</title>
</head>
<body>
    <script src="bundle.js"></script>
</body>
</html>webpack.config.js
var path = require('path');module.exports = {
    entry: './src/index.js',
    devServer: {
        contentBase: './dist'
    },
    output: {
        filename: 'bundle.js',
        path: path.resolve(__dirname, 'dist')
    }
};index.js
import _ from 'lodash';
function component() {
    var element = document.createElement('div');    // Lodash, now imported by this script
    element.innerHTML = _.join(['Hello', 'webpack'], ' ');    return element;
}document.body.appendChild(component());package.json
{
  "name": "day43",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "webpack-dev-server --open"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "webpack": "^3.3.0",
    "webpack-dev-server": "^2.6.0"
  },
  "dependencies": {
    "lodash": "^4.17.4"
  }
}配置如上所示，配置好后，运行npm start之后报错：
ERROR in (webpack)-dev-server/client?http://localhost:8080
Module not found: Error: Can't resolve 'loglevel' in '/Users/qinqinqin/Desktop/IFE-2017/day43/node_modules/webpack-dev-server/client'
 @ (webpack)-dev-server/client?http://localhost:8080 4:10-29
 @ multi (webpack)-dev-server/client?http://localhost:8080 ./src/index.js不知道是什么原因，求大神指导，跪谢！