Merge remote-tracking branch 'origin/develop' into develop

dist/vis.js

@@ -18489,7 +18489,7 @@ return /******/ (function(modules) { // webpackBootstrap
     }
 
     // copy group properties
-    if (this.group !== undefined) {
+    if (this.group !== undefined && this.group != "") {
       var groupObj = this.grouplist.get(this.group);
       for (var prop in groupObj) {
         if (groupObj.hasOwnProperty(prop)) {

lib/network/Node.js

@@ -171,7 +171,7 @@ Node.prototype.setProperties = function(properties, constants) {
   }
 
   // copy group properties
-  if (this.group !== undefined) {
+  if (this.group !== undefined && this.group != "") {
     var groupObj = this.grouplist.get(this.group);
     for (var prop in groupObj) {
       if (groupObj.hasOwnProperty(prop)) {