title: paths is not working in tsconfig.app.json as expected
body: <p>I am using Angular to develop my website. And I wanna set a <code>BASE_API</code> for my project depends on <code>prod</code> or <code>dev</code>. Therefore, I add some code in <code>environment</code></p>
  
  <pre><code>  export const environment = {
      production: true,
      BASE_API: 'http://localhost:3000/',
    };
  </code></pre>
  
  <p>And I wanna use <code>import { environment } from '@environments/environment'</code> to import instead of <code>import { environment } from '../../../environments/environment';</code> So I set <code>tsconfig.app.json</code> just like below</p>
  
  <pre><code>  {
      "extends": "../tsconfig.json",
      "compilerOptions": {
        "outDir": "../out-tsc/app",
        "module": "es2015",
        "baseUrl": "./",
        "paths": {
          "@angular/*": [
            "../node_modules/@angular/*"
          ],
          "@environments/*": [
            "../src/environments/*"
          ]
        }
      },
    }
  </code></pre>
  
  <p>And my project structure as below</p>
  
  <pre><code> src
      app
      environments
              environment.prod.ts
              environment.ts
  </code></pre>
  
  <p>However, the VSCode shows:</p>
  
  <blockquote>
    <p>ERROR in src/app/user/article/article.service.ts(3,29): error TS2307: Cannot find module '@environments/environment'.</p>
  </blockquote>
  
  <p>How can I fix this problem?</p>