async getLastStats() {
    if (!this.enabled) {
      throw errorStats.get("not_available");
    }

    const frame = Object.assign(
      { timestamp: new Date().getTime() },
      this.currentStats,
    );

    if (!this.lastFrame) {
      return frame;
    }

    const last = await global.kuzzle.ask(
      "core:cache:internal:get",
      this.cacheKeyPrefix + this.lastFrame,
    );

    return Object.assign(frame, JSON.parse(last));
  }
Gets stored statistics frames from a date

@returns {Promise}