Merge pull request +6415 from c9/improve-docker

[Trivial] Fix raygun error

node_modules/vfs-socket/worker.js

@@ -168,7 +168,7 @@ function Worker(vfs) {
         streams[id] = stream;
         stream.id = id;
         stream.on("error", function(err) {
-            remote.onError(id, err);
+            remote.onError && remote.onError(id, err);
         });
         if (stream.readable) {
             stream.on("data", function (chunk) {