title: Type 'boolean' is not assignable to type 'false'
body: <p>I'm developing a app with several other people and today I pulled master and all of a sudden while building I'm receiving an error:</p>
  
  <blockquote>
    <p>Type 'boolean' is not assignable to type 'false'.</p>
  </blockquote>
  
  <p>Another colleague is also running into this issue, but several other developers are not having this issue. We're all running the same tsconfig.json. </p>
  
  <p>I've updated TypeScript and we're all running Node v10+.</p>
  
  <p>What could cause the discrepancy between our systems?</p>