Unusual NullReferenceException Involving Character Death and following Orb

Questions & Answers
1

Alright this is probably going to take some time so I’ll get straight into it, I am working on a rogue-like dungeon crawler and I’ve been encountering some issues featuring the enemy type nicknamed the Mage, Every 2 seconds it Instantiates an orb that follows the player using the following script:

public Collider2D self;
    public float moveSpeed;
    public float attackDamage;
    Transform Player;
    bool temp;
    void Start() {
        if(PlayerState.health > 0f && GameObject.FindWithTag("Player").transform != null){
            Player = GameObject.FindWithTag("Player").transform;
        }
    }
    void Update(){
        if(PlayerState.health > 0f && Player != null && GameObject.FindWithTag("Player") != null) {
            transform.position = Vector2.MoveTowards(transform.position, Player.position, moveSpeed * Time.deltaTime);
        }
        if(PlayerState.health <= 0f) {
            gameObject.SetActive(false);
            Destroy(gameObject);
        }
    }

The line “Player = GameObject.FindWithTag(“Player”).transform;” throws a NullReferenceException when the player dies. In the script above you can witness my futile attempts to fix this, which have all returned unsuccessful. The player’s Death is handled with the next script:

void Reset () {
        Debug.Log("PLAYER SHOULD BE DEAD REEEEEEEEEEE");
        RoomSpawner.deleteAllRooms();
        SceneManager.LoadScene("Prison");

    }
    IEnumerator DeathAnimation() {
        Player.SetActive(false);
        deathEffect.Play();
        yield return new WaitForSeconds(1.5f);
        Reset();
    }

In theory, these are all the scripts affecting this issue, and it’s rather important since death is a pretty important part of a roguelike. What could be done to either make this script better or simply make it WORK again.

2

Best thing to do is make an object of player(instead of transform), and declare it in start, with the find logic. So only if player != null would be used in the update. Most things like GetComponent and GameObject.Find are very slow, so code runs several times in frames before that fully does it’s coroutine. So avoid using them during runtime and while in update.

public GameObject player;

void Start() 
{
         if(PlayerState.health > 0f)
             player = GameObject.FindWithTag("Player");
}

But always put if not null first in the argument:

void Update()
{
    if(Player != null && PlayerState.health > 0f) 
    {
        transform.position = Vector2.MoveTowards(transform.position, player.transform.position, moveSpeed * Time.deltaTime);
    }

     if(PlayerState.health <= 0f)
             Destroy(gameObject);
}

And also you might just wish to use a Object Pool if you plan on destroying and re-instantiating a lot. Cuts down on game lag, and if player is always there during the scene, the start only needs read once.
I would research into those ;)