A simple way to avoid unknown errors in Sass maps is to always use quotes on the map keys.
WordPress 4.9 is out and if you are hosting on the Pantheon platform, you can use this bash script to update core easily using Terminus.
Recently I changed my post URLs to include the category before the post slug. While this is a redirect that WordPress can usually handle, I found that redirects coming from my old URL were not routing correct and this snippet fixes that issue.
Quick command to stop a stuck Virtual Box instance, just in case there is nothing else works (CLI, app or otherwise).