(SOLVED) Getting NullReferenceException for seemingly no reason?

I'm trying to spawn in prefabs using Object.Instantiate from a prefab I pass in through the inspector. Everything else seems to be working except Instantiate, it keeps bringing up a NullReferenceException error, like I'm giving it an empty variable. Yes, I did assign an object in the inspector, and I tried others, but nothing works.

Code (CSharp):

1. // I'll only show relevant code
2.  
3. // enemy spawning variables
4.     // enemy spawning variables
5.     private Vector3[] spawnPoints;
6.     public GameObject enemyA;
7.     private float timeSurvived, spawnTimer, timeBetweenSpawns;
8.     public int tracked, difficulty; // currently alive and the max
9.  
10. // ...
11.  
12. // update time survived and spawn enemies
13.     void Update()
14.     {
15.         timeSurvived += Time.deltaTime;
16.         spawnTimer -= Time.deltaTime;
17.  
18.         // if the timer is ready and a slot's available
19.         if (spawnTimer < 0.0f && tracked < difficulty)
20.         {
21.             Debug.Log("lmao");
22.             Object.Instantiate(enemyA, spawnPoints[Random.Range(0, 8)], Quaternion.identity);
23.             timeBetweenSpawns = 1.0f;
24.             spawnTimer = timeBetweenSpawns;
25.             CalculateDifficulty();
26.             tracked++;
27.         }
28.     }

I'm starting to suspect that this is a Unity bug. Any thing wrong here?

 

On your debug log in line 21, try:

Code (csharp):

1. Debug.Log("enemyA is "+(enemyA != null ? "not null" : "null", this);

What does it say there?

It's possible you have accidentally added the script to another object in your scene; one may have the correct reference assigned, one may not, and the second will be triggering the error. If so, then clicking on the above will take you to the object with the error.

 

Hey, can you change the debug to

Debug.Log("lmao " + (enemyA == null ? "Im null" : ""+enemyA));

and tell us what you get?

 

Have you actually filled your 'spawnpoints' variable?

 

The nullref might be spawnPoints. Have you tried Debug.Log on all parts of the line?

 

"enemyA is (not null, Player (PlayerController))"

I tried switching out my spawnPoints for just a plain ol' vector3 and suddenly it's working! Here's the code setting them up (it's supposed to be a list of possible points to spawn at):

Code (CSharp):

1. // enemy spawning variables
2.     private Vector3[] spawnPoints;
3.  
4. // Start is called before the first frame update
5.     void Start()
6.     {
7.         // create spawn points
8.         Vector3[] spawnPoints = new Vector3[8];
9.         spawnPoints[0] = new Vector3(-6.0f, -10.0f, 0.0f);
10.         spawnPoints[1] = new Vector3(-6.0f, -6.0f, 0.0f);
11.         spawnPoints[2] = new Vector3(-6.0f, -2.0f, 0.0f);
12.         spawnPoints[3] = new Vector3(6.0f, -10.0f, 0.0f);
13.         spawnPoints[4] = new Vector3(6.0f, -6.0f, 0.0f);
14.         spawnPoints[5] = new Vector3(6.0f, -2.0f, 0.0f);
15.         spawnPoints[6] = new Vector3(-2.0f, -10.0f, 0.0f);
16.         spawnPoints[7] = new Vector3(2.0f, -10.0f, 0.0f);
17.     }

 

Your mistake is you have a class variable named spawnPoints, but then you create a local variable named spawnPoints. These are not the same variable.

So your class variable is empty, your local one gets populated, but then discarded once Start is exited.
Remove the Vector3[] from the Start variable

 

Success! Thank you everyone, everything is working properly now!