What am I doing wrong? (NullReferenceException)

I've been working on Unity's Space Shooter tutorial by adding new elements to the game. I made an array of powerups for one script but wanted to clean it up. I made another project from scratch and separated the PlayerController script into movement, weapon, and powerup scripts. Now, I'm getting an error that I wasn't getting when it was all on one script. Here's the original:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. [System.Serializable]
5. public class Boundary
6. {
7.     public float xMin, xMax, zMin, zMax;
8. }
9.  
10. public class PlayerController1 : MonoBehaviour
11. {
12.     private Rigidbody rb;
13.     private AudioSource audioSource;
14.  
15.     private float nextFire;
16.  
17.     public Boundary boundary;
18.     public GameObject shot;
19.  
20.     public Transform shotSpawn;
21.     public GameObject[] powerUps;
22.     public Vector3 spawnValues;
23.  
24.     public float speed;
25.     public float tilt;
26.     public float fireRate;
27.     public float timer;
28.     public float startWait;
29.     public float spawnWait;
30.  
31.     void Start()
32.     {
33.         rb = GetComponent<Rigidbody>();
34.         audioSource = GetComponent<AudioSource>();
35.  
36.         StartCoroutine(SpawnPowerups());
37.     }
38.  
39.     private void Update()
40.     {
41.         if (Input.GetButton("Fire1") && Time.time > nextFire)
42.         {
43.             nextFire = Time.time + fireRate;
44.  
45.             Instantiate(shot, shotSpawn.position, shotSpawn.rotation);
46.             audioSource.Play();
47.         }
48.  
49.         timer -= Time.deltaTime;
50.  
51.         if (timer <= 0)
52.         {
53.             fireRate = 0.25f;
54.         }
55.     }
56.  
57.     private void FixedUpdate()
58.     {
59.         float moveHorizontal = Input.GetAxis("Horizontal");
60.         float moveVertical = Input.GetAxis("Vertical");
61.  
62.         Vector3 movement = new Vector3(moveHorizontal, 0f, moveVertical);
63.         rb.velocity = movement * speed;
64.  
65.         rb.position = new Vector3
66.         (
67.             Mathf.Clamp(rb.position.x, boundary.xMin, boundary.xMax),
68.             0f,
69.             Mathf.Clamp(rb.position.z, boundary.zMin, boundary.zMax)
70.         );
71.  
72.         rb.rotation = Quaternion.Euler(0f, 0f, rb.velocity.x * -tilt);
73.     }
74.  
75.     private void OnTriggerEnter(Collider other)
76.     {
77.  
78.         if(other.CompareTag("Boundary"))
79.         {
80.             return;
81.         }
82.  
83.         if (powerUps[0])
84.         {
85.             timer = 5f;
86.             Debug.Log(other);
87.             if (timer > 0f)
88.             {
89.                 fireRate = fireRate / 2;
90.             }
91.         }
92.         Destroy(other.gameObject);
93.     }
94.  
95.     IEnumerator SpawnPowerups()
96.     {
97.         yield return new WaitForSeconds(startWait);
98.         while (true)
99.         {
100.             GameObject powerUp = powerUps[Random.Range(0, powerUps.Length)];
101.             Vector3 spawnPosition = new Vector3(Random.Range(-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
102.             Instantiate(powerUp, spawnPosition, Quaternion.identity);
103.  
104.             yield return new WaitForSeconds(spawnWait);
105.         }
106.     }
107. }

Btw, I was playing around with time because I wanted to learn more about it, but decided Coroutines are a better way to go for what I'm trying to accomplish. Anyway, in this script, the code works the way I want it to. When I collide with the Rapid Fire powerup, I shoot twice as fast. The set of scripts aren't placed on the player, but instead on an Empty Game Object (Spawn Powerups) and the individual powerups (Powerup Manager). When I collide with these, even though there's a reference to the array of powerups and I'm trying to reference the particular powerup I have in the Element slot in the inspector, it still gives me an error:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class SpawnPowerups : MonoBehaviour
5. {
6.     public GameObject[] powerups;
7.     public Vector3 spawnValues;
8.  
9.     private float delay;
10.  
11.     private void Start()
12.     {
13.         delay = Random.Range(10, 20);
14.         StartCoroutine(PowerupSpawn());
15.     }
16.  
17.     public IEnumerator PowerupSpawn()
18.     {
19.         Vector3 spawnPosition = new Vector3(Random.Range(-spawnValues.x, spawnValues.x), spawnValues.y, spawnValues.z);
20.         yield return new WaitForSeconds(delay);
21.  
22.         while (true)
23.         {
24.             GameObject powerup = powerups[Random.Range(0, powerups.Length)];
25.             Instantiate(powerups[Random.Range(0, powerups.Length)], spawnPosition, Quaternion.identity);
26.             yield return new WaitForSeconds(delay);
27.         }
28.     }
29. }

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3.  
4. public class PowerupManager : MonoBehaviour
5. {
6.     SpawnPowerups spawn;
7.     PlayerWeapon weapon;
8.  
9.     private float duration = 5f;
10.     private bool meshRendererActive;
11.     private bool spawnColliderActive;
12.  
13.     [HideInInspector]
14.     public bool isInvincible = false;
15.  
16.     private void Start()
17.     {
18.         meshRendererActive = GetComponentInChildren<MeshRenderer>().enabled;
19.         spawnColliderActive = GetComponent<Collider>().enabled;
20.         SpawnPowerups spawn = GetComponent<SpawnPowerups>();
21.         PlayerWeapon weapon = GetComponent<PlayerWeapon>();
22.     }
23.     private void OnTriggerEnter(Collider other)
24.     {
25.  
26.         if (other.CompareTag("Player"))
27.         {
28.         meshRendererActive = false;
29.         spawnColliderActive = false;
30.  
31.             if (spawn.powerups[0])
32.             {
33.                 StartCoroutine(RapidFire(other));
34.                 Destroy(gameObject);
35.             }
36.  
37.             else if (spawn.powerups[1])
38.             {
39.                 StartCoroutine(Invincible(other));
40.                 Destroy(gameObject);
41.             }
42.         }
43.     }
44.  
45.     IEnumerator RapidFire(Collider player)
46.     {
47.         weapon.fireRate /= 2;
48.         yield return new WaitForSeconds(duration);
49.         weapon.fireRate *= 2;
50.     }
51.  
52.     IEnumerator Invincible(Collider other)
53.     {
54.         isInvincible = true;
55.         yield return new WaitForSeconds(duration * 2);
56.         isInvincible = false;
57.     }
58. }

I've considered putting all of this in a single script, but also don't know how to reference child game objects to be disabled and destroyed.

 

P.S. The error is happening on line 31 of the 3rd script.

 

spawn is a private in that third script.

Where is it initialized?

 

I just changed it to public and it still didn't work. I initialized it in Start but changed it to OnTriggerEnter and I'm getting the same error.

 

Right before line 31, print its value with:

Code (csharp):

1. Debug.Log(spawn);

If it's null, maybe you inadvertently dragged this script on another GameObject, or something else nulled it after you set it in the inspector.

 

Well first thing to find out is if spawn or [0] is null so debug.log that first?
Also to that child question:
this gets the first child in the hierarchy and disables it.
transform.GetChild (0).gameObject.SetActive (false);

 

It returned null. I checked everything in the inspector, but only the powerup prefabs have that script attached. I don't know what you mean by something else nulled.

 

Debug.Log(spawn) returns null and (spawn.powerups[0]) doesn't return anything. If I can't figure it out with separate scripts, I'll just combine those two.

 

I decided I couldn't figure out why the reference was null, so I just created a GameObject to fix it for me.

Code (CSharp):

1. GameObject spawnGameObject = GameObject.FindWithTag("Spawn Manager");
2.  
3. spawn = spawnGameObect.GetComponent<SpawnPowerups>();