Craft 3 404 and 503 pages in devMode Is there any way to get Craft 3 to display 404.html and 503.html for the 404 and 503 pages while in devMode, as it did in Craft 2, rather than returning the entire Yii 2 error stack?

Sometimes, we have to bring a site temporarily offline (by way of toggle in the general settings tab) to add features, and we have to put it into dev mode for debug. We want the site to show the branded 503 page to the public instead of the stack page.
Just posting this here since I saw an official answer in Github:


  This changed in Beta 7:
  
  UserException reports are now styled like other exceptions when Dev
  Mode is enabled, with the full stack trace shown.
  
  You can see your 404 template by requesting it directly, e.g. http://mysite.dev/404


https://github.com/craftcms/cms/issues/1613#issuecomment-293366095