title: Syntax validation of a custom language in Monaco editor
body: <p>I'm trying to integrate a custom language to monaco editor and I went through <a href="https://microsoft.github.io/monaco-editor/monarch.html" rel="noreferrer">https://microsoft.github.io/monaco-editor/monarch.html</a> to get an idea on syntax highlighting. </p>
  
  <p>But I couldn't find any doc on how we can add error/warning validations through syntax validation for this. In Ace editor we did this by writing a worker and performing validation function within it. Appreciate any links/help on this.</p>