Add null check
Add null check

When directly using Html.CascadingDropDownList() and the Model is null, then will result in a System.NullReferenceException (Detail s: https://github.com/alexanderar/Mvc.CascadeDropDown/issues/22)
Li-Yanzhi/Mvc.CascadeDropDown,Li-Yanzhi/Mvc.CascadeDropDown,Li-Yanzhi/Mvc.CascadeDropDown