showExcitedState(duration) {
    return this.showIdleState(duration).then(() => {
      // Speed up the figure 8
      if (this._repeatingFigureEightAction != null) {
        this._repeatingFigureEightAction.setDuration(2.0);
      }
    });
  }
Shows the loot crate as excited.
@param {Number} [duration=0.5]
@public
@return {Promise}