make sure websocket is defined

package.json

 {
   "name": "remixd",
-  "version": "0.1.8-alpha.7",
+  "version": "0.1.8-alpha.9",
   "description": "remix server: allow accessing file system from remix.ethereum.org and start a dev environment (see help section)",
   "main": "./src/index.js",
   "bin": {

src/services/sharedFolder.js

@@ -15,7 +15,7 @@ module.exports = {
   sharedFolder: function (sharedFolder, readOnly) {
     this.sharedFolder = sharedFolder
     this.readOnly = readOnly
-    this.websocket.send(message('rootFolderChanged', {}))
+    if (this.websocket) this.websocket.send(message('rootFolderChanged', {}))
   },
 
   list: function (args, cb) {