Make sure to always execute onEndMove in Sorter

src/utils/Sorter.js

@@ -905,7 +905,7 @@ module.exports = Backbone.View.extend({
    * */
   endMove(e) {
     var created;
-    const moved = [];
+    const moved = [null];
     const docs = this.getDocuments();
     const container = this.getContainerEl();
     const onEndMove = this.onEndMove;