error WaitForEndOfFrame

Debug.Log("CollectorScene IECountDown totalSecond:" + totalSecond + "/" + Application.isBatchMode);
		int second = (int)totalSecond;
		while (totalSecond > 0)
		{
            totalSecond -= Time.deltaTime;
			Debug.LogFormat("CollectorScene IECountDown deltaTime:{0},totalSecond:{1}", Time.deltaTime, totalSecond);
            //Debug.LogError(totalSecond);
            second = (int)totalSecond;
			_time.text = string.Format("{0:00}:{1:00}", second / 60, second % 60);
			yield return new WaitForEndOfFrame();
            //yield return null;
        }