为什么我的应用程序不能在heroku上运行？

Question

当我在开发中运行它时，我的node.js应用程序运行良好，但是当我尝试在heroku上打开它时，它崩溃并显示错误代码H10和503状态代码。以下是控制服务器（/app/index.js）的代码：

const listen = (port) => {
  return new Promise((resolve, reject) => {
    return resolve(app.listen(port));
  });
};

exports.up = (justBackend) => {
  return db.migrate.latest([ENV])
    .then(() => {
      return db.migrate.currentVersion();
    })
    .then((val) => {
      console.log('Done running latest migration:', val);
      return listen(process.env.PORT || 3000);
    })
    .then((server) => {
      console.log(`Listening on port ${process.env.PORT} || 3000...`);
      return server
    });
}; 

起初，我只是将端口设置为3000，所以我添加了heroku可以动态设置端口的部分，但仍然出现相同的错误。也不确定该错误是否可能是由于我的package.json中的某物引起的，所以这也是：

{
  "name": "hand-tracker",
  "version": "1.0.0",
  "description": "A tool to track common trends in the poker hands I win and 
lose",
  "main": "index.js",
  "scripts": {
    "test": "export NODE_ENV=testing; mocha --recursive -R mocha-multi -- 
         reporter-options spec=-,json=.results.json",
    "start": "export NODE_ENV=development; node server.js"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/AdamT213/hand-tracker.git"
  },
  "author": "Adam Tropp",
  "license": "MIT",
  "bugs": {
    "url": "https://github.com/AdamT213/hand-tracker/issues"
  },
  "homepage": "https://github.com/AdamT213/hand-tracker#readme",
  "devDependencies": {
    "body-parser": "^1.18.3",
    "chai": "^4.1.2",
    "express": "^4.16.3",
    "jsdom": "^11.11.0",
    "lodash": "^4.17.10",
    "mocha": "^5.2.0",
    "mocha-jsdom": "^2.0.0",
    "mocha-multi": "^1.0.1",
    "supertest": "^3.1.0"
  },
  "dependencies": {
    "bookshelf": "^0.13.3",
    "connect-flash": "^0.1.1",
    "cookie-parser": "^1.4.3",
    "express-session": "^1.15.6",
    "knex": "^0.15.1",
    "passport": "^0.4.0",
    "passport-local": "^1.0.0",
    "pg": "^7.4.3"
  }
} 

**编辑：我在package.json中添加了一个heroku postbuild脚本，该脚本在生产环境中安装了dev依赖项，但是仍然出现相同的错误。当我运行heroku restart时，出现错误消息

2018-07-29T21：48：38.419242 + 00：00 app [web.1]：在环境中运行：开发 2018-07-29T21：48：38.575292 + 00：00 app [web.1]：未处理的拒绝错误：连接ECONNREFUSED 127.0.0.1:5432

我是否需要使启动脚本在生产环境中运行而不是在开发环境中运行？