title: Error when updating create-react-app to 4.0 with typescript template
body: <p>I want to update <code>react-scripts</code> to the next version (<code>4.0.0</code>) so I can use the fast refresh feature using this guide <a href="https://gist.github.com/iansu/282dbe3d722bd7231fa3224c0f403fa1" rel="noreferrer">here</a>. But when restarting the server, the script doesn't work because of the error below:</p>
  <pre class="lang-sh prettyprint-override"><code>$ yarn start
  yarn run v1.22.4
  $ react-scripts start
  E:\Github\Web\so-rank\node_modules\react-scripts\scripts\utils\verifyTypeScriptSetup.js:210
          appTsConfig.compilerOptions[option] = suggested;
                                              ^
  
  TypeError: Cannot add property noFallthroughCasesInSwitch, object is not extensible
      at verifyTypeScriptSetup (E:\Github\Web\so-rank\node_modules\react-scripts\scripts\utils\verifyTypeScriptSetup.js:210:45)
      at Object.&lt;anonymous&gt; (E:\Github\Web\so-rank\node_modules\react-scripts\scripts\start.js:31:1)
      at Module._compile (internal/modules/cjs/loader.js:1138:30)
      at Object.Module._extensions..js (internal/modules/cjs/loader.js:1158:10)
      at Module.load (internal/modules/cjs/loader.js:986:32)
      at Function.Module._load (internal/modules/cjs/loader.js:879:14)
      at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:71:12)
      at internal/main/run_main_module.js:17:47
  error Command failed with exit code 1.
  </code></pre>