Fix issue #723 to return better error
Fix issue #723 to return better error

https://github.com/Vizzuality/cartodb/issues/723

calvinmetcalf/CartoDB-SQL-API,CartoDB/CartoDB-SQL-API,calvinmetcalf/CartoDB-SQL-API,dbirchak/CartoDB-SQL-API,dbirchak/CartoDB-SQL-API,CartoDB/CartoDB-SQL-API,calvinmetcalf/CartoDB-SQL-API,calvinmetcalf/CartoDB-SQL-API,dbirchak/CartoDB-SQL-API,dbirchak/CartoDB-SQL-API