title: Typescript gives different errors in vscode than through webpack
body: <p>Visual Studio Code runs an instance of the typescript compiler internally to power the in-editor error feedback. You can choose which typescript to use with the <code>typescript.tsdk</code> setting.</p>
  
  <p>I now have a situation where I get a red underlining telling me about an error that I don't get when building through webpack with <code>ts-loader</code>. I don't see a warning during webpack building either.</p>
  
  <p>So apparently the build is different and I like to know how that can be the case.</p>
  
  <p>The error I'm getting specifically is a typescript regression in newer version that I could google in several projects. The message is:</p>
  
  <blockquote>
    <p>Expression produces a union type that is too complex to represent. ts(2590)</p>
  </blockquote>
  
  <p>This question isn't about that specific error though, but about how it can come that the in-editor typescript disagrees with the <code>ts-loader</code>-loaded one even though they are the same version.</p>