This line in the puppet-managed localsettings bit for VisualEditor's vagrant role:
$wgDefaultUserOptions['visualeditor-enable'] = 1;
seems to conflict with this default in VE's extension.json:
"DefaultUserOptions": { "visualeditor-enable": 0, ...
resulting in a combined default of:
array( 1, 0 )
This breaks in User::getOptions:
( ! ) Notice: Array to string conversion in /vagrant/mediawiki/includes/User.php on line 2563