block state updates while command is in flight

[rkuhn]

Currently the user needs to defend against getting an unrelated state update originating from a network event immediately after invoking a command:

let thingDone = false
for await (const state of machine) {
  if (state.is(SomeState) && !thingDonw) {
    state.cast().commands()?.doTheThing()
    thingDone = true
  }
}

It would be nicer and more intuitive if the next loop iteration was guaranteed to contain the information that was published via the doTheThing action (which usually will be reflected in transitioning to a new state, but might also just add something to the current state).