Как убрать ошибку NullReferenceException: Object reference not set to an instance of an object Damage.OnCollisionEnter2D в файле Damage.cs

Полная ошибка:

NullReferenceException: Object reference not set to an instance of an object
Damage.OnCollisionEnter2D (UnityEngine.Collision2D collision) (at Assets/Scripts/Damage.cs:9)

когда Игрок касаеться шипа, он должен получить урон в размере -1 жизни. Но выдает эту ошибку.

Cкрипт шипа Damage.cs:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Damage : MonoBehaviour
{
    private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.gameObject == Hero.Instance.gameObject)
        {
            Hero.Instance.GetDamage();
        }
        
    }
}

Функция Игрока (Hero.cs):

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Hero : MonoBehaviour
{
    [SerializeField] private float speed = 3f; //Скорость движения
    [SerializeField] private int lives = 5; //Колл-во жизней
    [SerializeField] private float jumpForce = 15f; //Сила прыжка
    private bool isGrounded = false;

    private Rigidbody2D rb;
    private Animator anim;
    private SpriteRenderer sprite;

    public static Hero Instance { get; set; }
    private States State
    {
        get { return (States)anim.GetInteger("State"); }
        set { anim.SetInteger("State", (int)value); }
    }

    private void Awake()
    {
        rb = GetComponent<Rigidbody2D>();
        anim = GetComponent<Animator>();
        sprite = GetComponentInChildren<SpriteRenderer>();
    }
    private void FixedUpdate()
    {
        CheckGround();
    }
    private void Update()
    {
        if (isGrounded) State = States.idle;
        if(Input.GetButton("Horizontal"))
        {
            Run();
        }
        if(isGrounded && Input.GetButtonDown("Jump"))
        {
            Jump();
        }

    }

    private void Run()
    {
        if (isGrounded) State = States.run;

        Vector3 dir = transform.right * Input.GetAxis("Horizontal");
        transform.position = Vector3.MoveTowards(transform.position, transform.position + dir, speed * Time.deltaTime);
        sprite.flipX = dir.x < 0.0f;
    }

    private void Jump()
    {
        rb.AddForce(transform.up * jumpForce, ForceMode2D.Impulse);

        if (!isGrounded) State = States.jump;
    }

    private void CheckGround()
    {
        Collider2D[] collider = Physics2D.OverlapCircleAll(transform.position, 0.3f);
        isGrounded = collider.Length > 1;

        if (!isGrounded) State = States.jump;
    }
    public void GetDamage()
    {
        lives -= 1;
        Debug.Log(1);
    }
}

public enum States
{
    idle,
    run,
    jump
}

Если что то еще надо пишите!