Restrict invoked Subscribable to EventObjects

[woutermont]

Currently, when invoking a Subscribable, the type is inferred to be Subscribable<any>, because this is hardcoded in the type definition of InvokeCreator. This makes any type inference/checking on its emissions impossible, even though the documentation states it is "expected to send events (strings or objects) to the parent machine".

Would there be any disadvantage to typing such an InvokeCreator as Subscribable<EventObject>?