What to do if Unity throws NullReferenceException: Object reference not set ot an instance of an object?

Question

Unity

I did a platformer according to the tutorial, and when it came to the implementation of bullets, the unit started throwing an error NullReferenceException: Object reference not set ot an instance of an object when trying to shoot, and pointed to a part of the code

public void Shoot()
    {
        Vector3 bulletspawn = transform.position; bulletspawn.y += 0.3f;
        State = CharState.Shoot;
        Instantiate(bullet, bulletspawn, bullet.transform.rotation);
    }

Namely, on the line Instantiate(bullet, bulletspawn, bullet.transform.rotation); and says that the reference to the object is not set to an instance of the object, although I have included all the references

private Bullet bullet;

private void Awake()
    {
        bullet = Resources.Load<Bullet>("Bullet");
    }

Here is the code for the bullet itself, in case it matters.

public class Bullet : MonoBehaviour
{
    private float speed = 10.0f;
    private Vector3 direction;
    public Vector3 Direction { set { direction = value; } }

    private SpriteRenderer sprite;

    private void Awake()
    {
        sprite = GetComponentInChildren<SpriteRenderer>();
    }

    private void Start()
    {
        Destroy(gameObject, 1.4f);
    }

    private void Update()
    {
        transform.position = Vector3.MoveTowards(transform.position, transform.position + direction, speed * Time.deltaTime);
    }
}

Answer 1

Theoretically, you are loading the Bullet component class from some Bullet prefab. And it remains without a GameObject, and therefore without a transform Link to the prefab in the editor by dragging it into the field AND instantiate without loading.
bullet = Resources.Load<Bullet>("Bullet");
public GameObject bullet;

Answer 2

debug and understand where you have null

Answer 3

Instead of

private Bullet bullet;

private void Awake()
    {
        bullet = Resources.Load<Bullet>("Bullet");
    }

It is easier to use public GameObject bulett;
A for the appearance of a bullet, you can use curotina:

public GameObject bullet;
void Start(){
StartCoroutine(SpawnBullet());
}
IEnumerator SpawnBullet()
    {
//в while нужно обязательно указать условие, при котором циклы будет выполняться.Если будет while(true), то это будет бесконечный цикл.
        while (true)
        {

           
            Instantiate(bullet, new Vector3(3 координаты через запятую. пример: 0f, 0f, 0f), Quaternion.identity);
            yield return new WaitForSeconds(время через которое будет спавниться пуля пример: 5f);




        }
    }

You hang this script on the enemy that shoots and indicate the condition of the coordinates and time. And in the inspector in the unit, specify the bullet prefab.
Ps With these values, the bullet will spawn while the scene is running, at coordinates 0, 0, 0 , every 5 seconds.