Fix addHandlerAsync and RemoveHandlerAsync
A recent update to the office.js api seems to have introduced an issue with Office.context.document.addHandlerAsync.
Running previously working code (Online Only, desktop excel seems ok) now gives a strange error, 'Function addHandlerAsync has invalid parameters'.
This can be replicated using the example on the api doc page here, hitting Try Me and just running the default code will show the message.
It also appears to have affected Office.context.document.removeHandlerAsync.
Sorry the API link is here: