fix error: this._taxonomies[namespace] is not Object

lib/WorkerFactory.js

@@ -62,6 +62,10 @@ WorkerFactory.prototype = {
       interestsUrlStopwords: interestsUrlStopwords
     });
 
+    if (variation == "edrules") {
+      this._taxonomies["edrules"] = this._extractCategories(interestsData);
+    }
+
     return worker;
   },