title: Typescript is not compiling `node_modules` folder
body: <p>I can't figure out why TypeScript isn't compiling anything that's inside the <code>node_modules</code> folder.</p>
  
  <p>Here is my <code>tsconfig.json</code>:</p>
  
  <pre><code>{
    "compilerOptions": {
      "rootDir": ".",
      "baseUrl": ".",
      "paths": {
        "shared": ["./src/shared"],
        "client": ["./src/client"],
        "server": ["./src/server"],
        "express": ["./node_modules/express"]
      },
      "plugins": [
        {"transform": "ts-transformer-imports"}
      ],
      "esModuleInterop": true,
      "allowJs": true,
      "target": "es2015",
      "module": "commonjs",
      "outDir": "./build"
    },  
    "files": ["./src/server/app.ts"]
  }
  </code></pre>
  
  <p>Inside <code>src/server/app.ts</code> I import both <code>express</code> and <code>shared</code>:</p>
  
  <pre><code>import shared from 'shared';
  import express from 'express';
  </code></pre>
  
  <p>The compilation succeeds, and compiled code for <code>shared</code> and <code>server</code> are generated. But, for some reason, the code for <code>express</code> isn't generated!?</p>
  
  <p>This makes absolutely no sense to me... does it randomly decide to not compile something just because it's in a folder called <code>node_modules</code>?</p>
  
  <p>How can I fix this?</p>
  
  <p><strong>Edit:</strong> I also tried changing it to <code>"express/*": ["./node_modules/express/*"]</code> in the config file, which didn't make any difference. (I don't know why it would, but I found that somewhere on the internet)</p>