Added a supply that notifies WebSocket Clients of closed connection

[holli-holzer]

No description provided.

[Altai-man]

What's the use case for this? Currently, when the server closes its connection, messages supply closes and that's an indication one wants.

[holli-holzer]

It'd be niceto be able to stay in the react/whenever semantics and get notified of a closing connection. Basically

my $conn = try await Cro::WebSocket::Client.connect( $some-server );

react 
{
    whenever $conn.messages -> $message 
    {
        say "Incoming: ", await $message.body;
    }

    whenever $conn.closing -> $reason
    {
        say "Closing: $reason";
        done;
    }
    
    whenever $user-input.command -> $command 
    {
        $conn.send( $command );
        CATCH { say "Error sending <$command>: {.message}" }
    }
};

If you have an alternative that is equally pretty or at least functional, please share.

Background: https://www.perlmonks.org/?node_id=11110913