_watchHashChanges() {
    this.set("urlHash", location.hash);
    window.addEventListener("hashchange", (event2) => {
      this.set("urlHash", location.hash);
      if (__privateGet(this, _sendUrlHash) === true) {
        this.send({ topic: "hashChange", payload: location.hash, newHash: this.keepHashFromUrl(event2.newURL), oldHash: this.keepHashFromUrl(event2.oldURL) });
      }
    });
  }
Set up an event listener to watch for hash changes
and set the watchable urlHash variable
@private