title: vscode does not show typescript error (angular)
body: <p>When I open the ts source in a angular project via vscode,there is no error message.</p>
  <pre><code>let toolbox = {
    'show': true,
    'feature': {}
  };
  if (saveAsImage) Object.assign(toolbox.feature, { saveAsImage: {} });
  if (restore) toolbox.feature['restore'] = {};
  </code></pre>
  <p>But when I copy this source file(only this ts source file) to other place and open it via vscode,the error message comes.</p>
  <pre><code>if (restore) toolbox.feature['restore'] = {};
  </code></pre>
  <p>If I need to modify angular config file to switch on error message or modify vscode config file?</p>
  <p>typescript version 3.9.5</p>
  <p>angular version 10.0.2</p>