Why is the GameObject null in Unity?

Question

I have a goal to create a bullet hole in the place where the ray hit, for this purpose I made a material, put a picture of a bullet hole on it, and sent the material itself to plane, and made it a prefab. I created a variable to which I threw this prefab:

public GameObject shootPF;

and I create it in the Instantiate() method:

if (Input.GetMouseButtonDown(0))
{
    Ray ray = _camera.ScreenPointToRay(Input.mousePosition);
    RaycastHit hit;

    if (Physics.Raycast(ray, out hit))
    {
        GameObject hitObject = hit.transform.gameObject;
        EnemyCodeD enemy = hitObject.GetComponent<EnemyCodeD>();
        if (enemy != null)
        {
            enemy.Hit();
        }
        else
        {
            Debug.Log(shootPF);
            Instantiate(
                shootPF,
                hit.point + (hit.normal * .01f),
                Quaternion.FromToRotation(
                Vector3.up,
                hit.normal
            )
        );
    }
}

The problem is that for some reason shootPF is null, although I passed everything in the inspector and there should be no problem with it. Why is that?

Answer 1

You should use logging and debug features to determine what is happening with your code:

if (Input.GetMouseButtonDown(0))
{
    Ray ray = _camera.ScreenPointToRay(Input.mousePosition);

    // Draw the ray in the Scene view in the Unity Editor for 10 seconds.
    Debug.DrawRay(ray.origin, ray.direction, Color.red, 10);

    RaycastHit hit;
    if (Physics.Raycast(ray, out hit))
    {
        GameObject hitObject = hit.transform.gameObject;

        // Log the object that was hit - click the log message in the Unity console to select the object in the Editor
        Debug.Log($"Hit {hitObject.name}", hitObject);

        EnemyCodeD enemy = hitObject.GetComponent<EnemyCodeD>();
        if (enemy != null)
        {
            Debug.Log("Hit object is an enemy");
            enemy.Hit();
        }
        else
        {
            Debug.Log("Hit something that isn't an enemy: " + shootPF);
            Instantiate(
                shootPF,
                hit.point + (hit.normal * .01f),
                Quaternion.FromToRotation(
                Vector3.up,
                hit.normal
            )
        );
    } else {
        Debug.Log("Raycast didn't hit anything");
    }
}

Notice that I've added logging for every possible path that your code can take. From the log messages, you will be able to tell exactly what is happening/going wrong. If the ray isn't hitting anything, look at the line that is drawn in the Scene view to make sure it's going where you expect. If it is, make sure that the object you're trying to click has a collider.