ECONNREFUSED when SubscriberOpen

My code:
```
var path = Path.GetDirectoryName(typeof(App).Assembly.Location);
var ctx = new NngLoadContext(path);
var factory = NngLoadContext.Init(ctx);
ISubSocket socketSub = factory.SubscriberOpen().ThenDial(url).Unwrap();
```

The ECONNREFUSED exception is raised if the publisher is not started, but not if the publisher is started.

Using the python wrapper of nng, no exception is reported in either case.