Hopefully fix occasional errors when trying to send an initial banner to a frame client. After looking through ws' source, the most likely reason seems to be that the websocket is in CLOSING state. Even if not, we should get a bit more useful log output this time.

lib/units/device/plugins/screen/stream.js

@@ -2,7 +2,7 @@ var util = require('util')
 
 var Promise = require('bluebird')
 var syrup = require('stf-syrup')
-var WebSocketServer = require('ws').Server
+var WebSocket = require('ws')
 var uuid = require('node-uuid')
 var EventEmitter = require('eventemitter3').EventEmitter
 var split = require('split')
@@ -400,7 +400,7 @@ module.exports = syrup.serial()
     function createServer() {
       log.info('Starting WebSocket server on port %d', screenOptions.publicPort)
 
-      var wss = new WebSocketServer({
+      var wss = new WebSocket.Server({
         port: screenOptions.publicPort
       , perMessageDeflate: false
       })
@@ -448,19 +448,59 @@ module.exports = syrup.serial()
           , JSON.stringify(frameProducer.banner)
           )
 
-          broadcastSet.values().forEach(function(ws) {
+          broadcastSet.keys().forEach(function(id) {
+            var ws = broadcastSet.get(id)
+            switch (ws.readyState) {
+            case WebSocket.OPENING:
+              // This should never happen.
+              log.warn('Unable to send banner to OPENING client "%s"', id)
+              break
+            case WebSocket.OPEN:
+              // This is what SHOULD happen.
               ws.send(message)
+              break
+            case WebSocket.CLOSING:
+              // Ok, a 'close' event should remove the client from the set
+              // soon.
+              break
+            case WebSocket.CLOSED:
+              // This should never happen.
+              log.warn('Unable to send banner to CLOSED client "%s"', id)
+              broadcastSet.remove(id)
+              break
+            }
           })
         })
 
         frameProducer.on('readable', function next() {
           var frame
           if ((frame = frameProducer.nextFrame())) {
-            Promise.settle([broadcastSet.values().map(function(ws) {
-              return new Promise(function(resolve/*, reject*/) {
+            Promise.settle([broadcastSet.keys().map(function(id) {
+              return new Promise(function(resolve, reject) {
+                var ws = broadcastSet.get(id)
+                switch (ws.readyState) {
+                case WebSocket.OPENING:
+                  // This should never happen.
+                  return reject(new Error(util.format(
+                    'Unable to send frame to OPENING client "%s"', id)))
+                case WebSocket.OPEN:
+                  // This is what SHOULD happen.
                   ws.send(frame, {
                     binary: true
-                }, resolve)
+                  }, function(err) {
+                    return err ? reject(err) : resolve()
+                  })
+                  return
+                case WebSocket.CLOSING:
+                  // Ok, a 'close' event should remove the client from the set
+                  // soon.
+                  return
+                case WebSocket.CLOSED:
+                  // This should never happen.
+                  broadcastSet.remove(id)
+                  return reject(new Error(util.format(
+                    'Unable to send frame to CLOSED client "%s"', id)))
+                }
               })
             })]).then(next)
           }

lib/units/device/plugins/screen/util/broadcastset.js

@@ -37,4 +37,12 @@ BroadcastSet.prototype.values = function() {
   }, this)
 }
 
+BroadcastSet.prototype.keys = function() {
+  return Object.keys(this.set)
+}
+
+BroadcastSet.prototype.get = function(id) {
+  return this.set[id]
+}
+
 module.exports = BroadcastSet