NullReferenceException: Object reference not set to an instance of an object Unity [дубликат]

Первый раз зашел в Unity, чтобы по видеоуроку сделать игру. И мне выдает такую ошибку, когда я пытаюсь стрельнуть в игре:

NullReferenceException: Object reference not set to an instance of an object Player.Shoot () (at Assets/Scripts/Player.cs:67) Player.Update () (at Assets/Scripts/Player.cs:45).

Класс персонажа:

public class Player : Unit
{
    [SerializeField]
    private int lives = 5;
    [SerializeField]
    private float speed = 3.0f;
    [SerializeField]
    private float jump_force = 15.0f;
    private CharState State
    {
        get { return (CharState)animator.GetInteger("State"); }
        set { animator.SetInteger("State", (int)value); }
    }
    new private Rigidbody2D rigidbody;
    private Animator animator;
    private SpriteRenderer sprite;
    private bool isGrounded = false;
    private Bullet bullet;
    private void Awake()
    {
        rigidbody = GetComponent<Rigidbody2D>();
        animator = GetComponent<Animator>();
        sprite = GetComponentInChildren<SpriteRenderer>();
        bullet = Resources.Load<Bullet>("Bullet");
    }
    private void FixedUpdate()
    {
        CheckGround();
    }
    private void Update()
    {
        if (isGrounded)State = CharState.Idle;
        if (Input.GetButtonDown("Fire1")) Shoot();
        if(Input.GetButton("Horizontal")) Run();
        if ( isGrounded && Input.GetButtonDown("Jump")) Jump();
    }
    private void Run()
    {
        Vector3 direction = transform.right * Input.GetAxis("Horizontal");
        transform.position = Vector3.MoveTowards(transform.position, transform.position + direction, speed * Time.deltaTime);
        sprite.flipX = direction.x < 0.0f;
        if (isGrounded) State = CharState.Run;
    }
    private void Jump()
    {
        rigidbody.AddForce(transform.up*jump_force, ForceMode2D.Impulse);
    }
    private void Shoot()
    {
        Vector3 position = transform.position; position.y += 0.8F;
        Bullet newBullet = Instantiate(bullet, position, bullet.transform.rotation) as Bullet;
    }
    private void CheckGround()
    {
        Collider2D[] colliders = Physics2D.OverlapCircleAll(transform.position, 3.0f);
        isGrounded = colliders.Length > 1;
        State = CharState.Jump;
    }
}
public enum CharState
{
    Idle,
    Run,
    Jump
}

Класс пули:

public class Bullet : MonoBehaviour
{
    private float speed=8.0f;
    private Vector3 direction;
    public Vector3 Direction { set { direction = value; } }
    private SpriteRenderer sprite;
    private void Awake()
    {
        sprite = GetComponentInChildren<SpriteRenderer>();
    }
    private void Update()
    {
        transform.position = Vector3.MoveTowards(transform.position, transform.position + direction, speed * Time.deltaTime);
    }
}