Update SchemaController.js

Author: dblythy

src/Controllers/SchemaController.js

@@ -151,7 +151,7 @@ const defaultColumns: { [string]: SchemaFields } = Object.freeze({
 });
 
 const requiredColumns = Object.freeze({
-  _User: 'username',
+  _User: ['username'],
   _Product: ['productIdentifier', 'icon', 'order', 'title', 'subtitle'],
   _Role: ['name', 'ACL'],
 });