When I specify cellFormatters: [expandable] as part of a column definition that's typed (ICell | string)[] (as directed in the docs) I get type errors.

I created a branch using pf-seed where you can easily see the problem. The implementation seems to be fine (live demo of the working branch here) but the types complain so I'm forced to supply a type of any[] in the mean time.

Am I just doing it wrong or is it a regression?