I haven't had time to find if there is an open issue and this is really about my config so leaving a note here in case it's useful. After a fresh install of Drupal 8 everything looked good. At least until I got to the Add Article page. The page said nothing but "Restricted HTML".
It's not quite a WSOD of old but it is still a PHP fatal. Looking through the log I found:
Fatal error: Maximum function nesting level of '100' reached, aborting! in .../drupal-8/core/vendor/twig/twig/lib/Twig/Node.php on line 141
The solution was to increase the xdebug limit on nesting by adding this to the php.ini in the xdebug section:
xdebug.max_nesting_level = 1000