Hm, seems to work for me with Swift 4.2. What version of Swift are you using?

@belkadan I'm using Swift 4.1. I just uploaded a video of the issue - perhaps though this has already been fixed in 4.2, which is great! Otherwise, let me know if there's any other info that would be helpful to you. And thank you for making Swift for the rest of us, it's really pretty great.

P.S. The error goes away for me if I change this:

init (reactor: Reactor, stateTransform: Reactor.StateTransform<Input>?)

{ self.reactor = reactor; self.stateTransform = stateTransform }

to this:

init (reactor: Reactor)

{ self.reactor = reactor }

@belkadan Wait nevermind the upload failed because the file is too big (50MB) - is there a better way for me to send it to you?

I've reproduced the crash on Swift 4.1 too, so I think we can just call this fixed!