报错信息：

NullReferenceException: Object reference not set to an instance of an object
PinHead.OnTriggerEnter2D (UnityEngine.Collider2D collision) (at Assets/Script/PinHead.cs:10)

代码：

public class PinHead : MonoBehaviour {

	private void OnTriggerEnter2D(Collider2D collision)
    {
        if (collision.tag == "Pinhead")
        {
            GameObject.Find("GameManager").GetComponent<GameManager>().GameOver();   //10
        }
    }
}

不挂载这个脚本时运行正常，挂载后报错