Warn on incorrect input

lib/DataSet.js

@@ -259,7 +259,11 @@ DataSet.prototype.update = function (data, senderId) {
   if (Array.isArray(data)) {
     // Array
     for (var i = 0, len = data.length; i < len; i++) {
-      addOrUpdate(data[i]);
+      if (data[i] instanceof Object){
+        addOrUpdate(data[i]);
+      } else {
+        console.warn("Ignoring input item, which is not an object at index"+i);
+      }
     }
   }
   else if (data instanceof Object) {