Type Error with json.arrayOf

[jeremy-coleman]

I'm having problems with the json.arrayOf,

even with copy/pasting the example,

class FancyItem {
@JSON firstName = "Homer";
@JSON lastName = "Simpson";
}

class HasFancyArray {
@JSON readonly fancyArray = json.arrayOf(FancyItem);
}

I get a type error saying typeof FancyItem is not assignable to type
new () => Partial Disposable