title: Cannot find module 'webpack-cli'
body: <p>I want to make es6 into my project so I used this tutorial <a href="https://medium.com/netscape/firebase-cloud-functions-with-typescript-and-webpack-7781c882a05b" rel="noreferrer">this tutorial</a>
  and when i try to write 'webpack' in cmd I get the error</p>
  
  <pre><code>    Done in 8.99s.
  { Error: Cannot find module 'webpack-cli'
      at Function.Module._resolveFilename (module.js:470:15)
      at Function.Module._load (module.js:418:25)
      at Module.require (module.js:498:17)
      at require (internal/module.js:20:19)
      at runCommand.then.result (C:\Users\adirz\AppData\Roaming\npm\node_modules\webpack\bin\webpack.js:62:14)
      at process._tickCallback (internal/process/next_tick.js:109:7) code: 'MODULE_NOT_FOUND' }
  </code></pre>
  
  <p>package.json</p>
  
  <pre><code>   {
    "name": "functions",
    "scripts": {
      "build": "tsc",
      "serve": "npm run build &amp;&amp; firebase serve --only functions",
      "shell": "npm run build &amp;&amp; firebase functions:shell",
      "start": "npm run shell",
      "deploy": "firebase deploy --only functions",
      "logs": "firebase functions:log"
    },
    "main": "lib/index.js",
    "dependencies": {
      "firebase-admin": "~5.12.0",
      "firebase-functions": "^1.0.1"
    },
    "devDependencies": {
      "ts-loader": "^4.2.0",
      "typescript": "^2.5.3",
      "webpack": "^4.5.0",
      "webpack-cli": "^2.0.14",
      "webpack-node-externals": "^1.7.2"
    },
    "private": true
  }
  </code></pre>
  
  <p>my folder structure</p>
  
  <p><a href="https://i.stack.imgur.com/AECzu.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/AECzu.jpg" alt="enter image description here"></a></p>