Webpack，ReactJS - 未捕获错误：ReactDOM.render（）：无效的组件元素

Question

我在Uncaught Error: ReactDOM.render(): Invalid Component element收到了wepack:///...invariant.js。 这是我的package.json和webpack.config.js：

{
  "name": "githubOauth",
  "version": "1.0.0",
  "description": "",
  "main": "webpack.config.js",
  "scripts": {
    "setup:init": "npm-run-all --parallel start:db setup:db setup:ssl",
    "setup:ssl": "hz create-cert && mv *.pem config/tls",
    "setup:db": "./config/rethinkdb/setup.sh",
    "start:db": "rethinkdb",
    "start": "webpack && node server.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "babel-cli": "^6.18.0",
    "babel-core": "^6.13.2",
    "babel-loader": "^6.2.5",
    "babel-polyfill": "^6.13.0",
    "babel-preset-es2015": "^6.18.0",
    "babel-preset-react": "^6.11.1",
    "babel-preset-stage-0": "^6.5.0",
    "npm-run-all": "^2.3.0",
    "webpack": "^1.9.10",
    "webpack-bundle-tracker": "0.0.51",
    "webpack-node-externals": "^1.5.4",
    "json-loader": "^0.5.4"
  },
  "dependencies": {
    "@horizon/client": "^2.0.0",
    "@horizon/server": "^2.0.0",
    "express": "^4.14.0",
    "path": "^0.12.7",
    "react": "^15.3.1",
    "react-dom": "^15.3.1",
    "react-router": "^2.7.0"
  }
}

和

var path = require('path');

module.exports = {
    entry: ["./src/app.js"],

    output: {
        filename: "dist/js/bundle.js",
        sourceMapFilename: "dist/js/bundle.map"
    },
    externals: {
        React: 'react'
    }, 

    devtool: '#source-map',
    resolve: {
      fallback: './node_modules'
    },
    resolveLoader: {
        root: [
            path.join(__dirname, "node_modules")
          ],
       fallback: './node_modules',
       modulesDirectories: [
          './node_modules'
      ]
    },
    module: {
        loaders: [
            { 
                test: /\.json$/, 
                loader: 'json-loader' 
            },
            {
                loader: 'babel',
                exclude: /node_modules/
            }
        ]
    },
    node: {
        console: 'empty',
        fs: 'empty',
        net: 'empty',
        tls: 'empty'
      }
}

这是我的控制台错误快照：