node.js - Trying to deploy React Webpack app to Heroku, keep getting 'Uncaught Error: Cannot find module "./src/index.js"' error -

i'm trying deploy heroku, , build successful; however, blank screen , console has error:

'uncaught error: cannot find module "./src/index.js"' 

also, while deploying, have following error:

error in loader /tmp/build_ad82f59a947c9639c358909b17671d27/node_modules/babel/index.js?{"presets":["react","es2015","stage-1"]} didn't return function 

in local environment, have .env file private access tokens , use dotenv retrieve secret keys when make api call. have set config variables on heroku. when in heroku logs, error:

2016-09-12t22:16:15.191754+00:00 app[web.1]: > node server.js 2016-09-12t22:16:15.191755+00:00 app[web.1]: 2016-09-12t22:16:15.686543+00:00 app[web.1]: { [error: enoent: no such file or directory, open '.env'] errno: -2, code: 'enoent', syscall: 'open', path: '.env' } 

here's webpack.config.js:

module.exports = { entry: [   './src/index.js' ], output: {   path: __dirname,   publicpath: '/',   filename: 'bundle.js' }, module: { loaders: [{   exclude: /node_modules/,   loader: 'babel',   query: {     presets: ['react', 'es2015', 'stage-1']   } }, {   test: /\.jsx?$/,   loaders: ['babel'],   exclude: /node_modules/ }, {    test: /\.css$/,    loader: 'style-loader!css-loader'  }, {   test: /\.(png|jpg)$/,   loader: 'url?limit=25000' }] }, resolve: {   extensions: ['', '.js', '.jsx'] }, devserver: {   historyapifallback: true,   contentbase: './' } }; 

here's package.json:

"devdependencies": {   "babel-core": "^6.2.1",   "babel-loader": "^6.2.0",   "babel-preset-es2015": "^6.1.18",   "babel-preset-react": "^6.1.18",   "chai": "^3.5.0",   "chai-jquery": "^2.0.0",   "enzyme": "^2.4.1",   "jquery": "^2.2.1",   "jsdom": "^8.1.0",   "mocha": "^2.4.5",   "react-addons-test-utils": "^0.14.7",   "webpack-dev-server": "^1.14.0" }, "dependencies": {   "axios": "^0.13.1",   "babel-preset-stage-1": "^6.1.18",   "body-parser": "^1.15.2",   "dotenv": "^2.0.0",   "express": "^4.14.0",   "lodash": "^3.10.1",   "material-ui": "^0.15.2",   "react": "^15.3.0",   "react-dom": "^15.0.0",   "react-redux": "^4.0.0",   "react-router": "^2.0.1",   "react-tap-event-plugin": "^1.0.0",   "react-tweet": "^1.0.22",   "redux": "^3.0.4",   "twitter": "^1.3.0",   "webpack": "^1.12.9" } } 

here server.js:

var express = require('express'); var bodyparser = require('body-parser'); var twitter = require('twitter'); var path = require('path'); var app = express(); var port = process.env.port || 3000; var dotenv = require('dotenv');  dotenv.config();  const api_twitter_url = 'https://api.twitter.com/1.1/search/tweets.json';  var client = new twitter({   consumer_key: process.env.consumer_key,   consumer_secret: process.env.consumer_secret,   access_token_key: process.env.access_token_key,   access_token_secret: process.env.access_token_secret });  // configure express use body-parser middleware app.use(bodyparser.urlencoded({ extended: false, limit: '500mb' })); app.use(bodyparser.json({ limit: '500mb' }));  // serve static files index.html, css etc app.use( express.static( __dirname ) );  app.get('*', (req, res) => {   res.sendfile(path.resolve(__dirname), 'index.html'); });  app.post('/api/gettweets', function(req, res) {    var params = { q: req.body.searchquery + '+everlane', filter: 'media' };    client.get(api_twitter_url, params, function(error, tweets, resp) {        if (error) { console.log('error: ', error) }        if (!error) {         res.send(tweets);       }   }); });  app.listen(port, function() {    console.log('\nproduction express server running @ localhost:' + port); });