Sitecore Could not find configuration node: databases/database Core

While playing around in a development environment I loaded up the Sitecore admin area only to  be greeted with the error:

Could not find configuration node: databases/database[@id='core']

 It was down to a simple mistake where a new Visual Studio solution had deployed the default web.config over the Sitecore one. The fix is to restore the web.config from a backup or to get a new one off of a clean Sitecore install.