Race condition due to premature Promise keep in listener.

[bbkr]

$tunnel-server promise should be kept whenever .socket-port promise is kept, not when .listen is started.

Explained here: https://stackoverflow.com/questions/78984529/when-whenever-block-in-react-section-starts-processing-events/78986120#78986120

[massa]

This is a nice catch (I was stomped on this, and the client I have for this library was using a sleep to evade the race...). Thank you very much! A newer release is following!