Publish does not fail when there are no sockets subscribed to channel.

I am using the below code within worker.js to allow a back end PHP script to push messages to clients.

The err function never executes even when there are no sockets subscribed to the channel.

Is there some way to detect when there are no active subscriptions to a channel?

app.post('/push', (request, response) => {
    const postBody = request.body;
    console.log("Received push message for : " + postBody['channelid'] + " From : " + request.connection.remoteAddress);
    var message = new Object();
    message.type="alert";
    message.data=postBody['messagedata'];
    scServer.exchange.publish(postBody['channelid'],message, function (err) {
        if (err) {
        // Failed to publish event, retry or let the user know and keep going?
        console.log("Push Failed");
        response.sendStatus(500)
        response.end();
    } else {
        // Event was published successfully
        console.log("Push Sent to Channel");
        response.sendStatus(200)
        response.end();
    }
    });
});

Start with worker.js and the /push handler's scServer.exchange.publish call; read the publish callback contract and channel subscription behavior. Reproduce the request with no subscribed sockets and determine whether the requested detection is supported. Done means the behavior is clarified or a documented, tested way to detect inactive subscriptions is identified.