Cached reference deleting itself

I'm going mad here and I'm certain I'm missing something obvious but I cannot work it out.

I have a script that controls the behaviour of a ball in my game, these are instantiated constantly whilst the game is active.

Code (CSharp):

1. public class BallBehaviour : MonoBehaviour
2. {
3.     private Rigidbody2D rb;
4.     [SerializeField]
5.     private float nudgeVelocity;
6.     public string specialType;
7.     public SpriteRenderer currentRenderer;
8.     private Color currentColor;
9.     //public GameObject gameController;
10.     //public GameObject bgEffect;
11.     public GameObject debris;
12.        
13.     // Start is called before the first frame update
14.     void Start()
15.     {
16.         currentRenderer = GetComponent<SpriteRenderer>();
17.  
18.         //This log statement returns "Gameplay", which is correct for the SpriteRenderer
19.         Debug.Log(currentRenderer.sortingLayerName);
20.  
21.         rb = GetComponent<Rigidbody2D>();
22.         //TODO Refine effects to different script
23.         //Disables 'halo' for negative balls
24.         if(specialType == "minus")
25.         {
26.             //bgEffect.SetActive(false);
27.         }
28.         currentColor = currentRenderer.color;
29.     }
30.  
31.     // Update is called once per frame
32.     void FixedUpdate()
33.     {
34.         CheckStuck();
35.         //Check height of ball to destroy once off screen
36.         if(transform.position.y < -5.5f)
37.         {
38.             DestroyBall();
39.         }
40.     }
41.    
42.     void CheckStuck()
43.     {
44.         if (rb.velocity.y == 0 && rb.velocity.x == 0)
45.         {
46.             rb.velocity = new Vector3(nudgeVelocity, 0f, 0f);
47.         }
48.     }
49.     void DestroyBall()
50.     {
51.         Destroy(gameObject);
52.     }
53.     void OnCatch()
54.     {
55.         DestroyBall();
56.     }
57.     void OnBreak()
58.     {
59.         GameObject spawnedDebris = Instantiate(debris, transform.position, transform.rotation);
60.         DebrisBehaviour spawnedBehaviour = spawnedDebris.GetComponent<DebrisBehaviour>();
61.         spawnedBehaviour.ChangeColor(currentColor);
62.         DestroyBall();
63.     }
64.     public void ChangeColor (Color inputColor)
65.     {
66.         Debug.Log("ChangeColor passed in: " + inputColor);
67.  
68.         //The below Debug statement throws an UnassignedReferenceException error for the currentRenderer field.
69.  
70.         Debug.Log(currentRenderer.sortingLayerName);
71.         currentRenderer.color = inputColor;
72.         currentColor = inputColor;
73.     }
74. }

As far as I can see, the script is correctly finding the SpriteRenderer component during Start() as my Debug statement correctly retrieves one of it's attributes, however by the time I have called ChangeColor from another script, it has 'forgotten' about that reference and throws an error.

I've used Visual Studio's Find All References to check I've not done something to it in another script somehow but the only references to currentRenderer are in the above code.

Can anyone see what I've done wrong or offer any clues as to why this is happening?

Thanks in advance,
Alex.

 

Some thoughts.

Are you calling ChangeColor to soon, before Start() has got the reference to the renderer?
Is the BallBehaviour script even enabled, and are you calling ChangeColor() of the right, and enabled, instance of the ball?

What does the error say in the Console?

 

You are 100% correct, arfish! I don't know quite enough about the order of execution in Unity to fully understand the sequence of events but moving my GetComponent requests from Start and into a new Awake method has solved the problem.

Many thanks!