f I have a columns like columns: `[{field: "Address.City"}]`, then it fails if Address is null. 

Uncaught TypeError: Cannot read property 'City' of undefined 

Expected: to handle nulls in parts of path in the same way as nulls in the leaf (e.g. City in this example). Not doing this, means we can't use the default template, sort or group functions on nested properties. 

Simple Dojo snippet to repro. 
http://dojo.telerik.com/AGeTo