Pass the error to inject_listener_closed method

[tcharding]

If there is an error when the listener closes, found in the NetworkEvent::ListenerClosed reason field, we would like to pass it on to the inject_listener_closed() method so that implementors of this method have access to it.

Add an error parameter to inject_listener_closed. Convert the reason field from a Result to an Option and if there is an error pass Some(error) at the method call site.

Resolves: #1475

[tomaka]

Could you leave the Result for consistency with the rest of the library?

Suggested change

	fn inject_listener_closed(&mut self, _id: ListenerId, _err: Option<std::io::Error>) {
	fn inject_listener_closed(&mut self, _id: ListenerId, reason: Result<(), io::Error>) {

[tcharding]

Sure thing, can do.

[tcharding]

After the merge conflicts are fixed we get left with this (buggy) code:

for addr in addresses.iter() {
    this.behaviour.inject_expired_listen_addr(addr);
}
this.behaviour.inject_listener_closed(listener_id, reason);
return Poll::Ready(SwarmEvent::ListenerClosed {
    addresses,
    reason,
});

The compiler error is that reason (due to the error being io::Error) does not implement Copy or Clone. Seems like we have to make a choice, either pass it to the trait method (inject_listener_closed) or pass it up in the event - we cannot do both. Any thoughts please @tomaka?

[tomaka]

Please pass the error by reference to inject_listener_closed

[tomaka]

I took the liberty to finish the change, I hope that's ok.
It would be nice to get this PR in the next release, and this next release has already been waiting for a long time.

[tcharding]

Please pass the error by reference to inject_listener_closed

Face palm - obviously. Thanks for finishing it. FTR feel free to take, modify, paraphrase, or drop anything I contribute. I'm just here to learn a bit and help out where it helps :)

Thanks.