(SOLVED) Accessing (string) arrays by enumerations from another class

Edit: I figured it out, I was instancing the class in Start() rather than Awake() and it was called too soon to exist.

Hello, first post; hopefully this goes to the correct forum. I've been slowly learning Unity, however I'm quite new to C# as well, so there's a fair change my code has mistakes or general weirdness. Feel free to point out any of those.

What I'm trying to do: Have a class that contains a string array accessible from other classes, using related enumerations as array indexes to point to the correct strings.

Or, put simpler, I want a list of integers that always point to the same thing, and also have a string value (eg. filename) associated with them that I can access.

Here's a stripped down example of what I have thus far:

 // This class holds info I want to access from elsewhere. Connected to a separate gameobject.
 public class StuffToAccess : MonoBehaviour {
     
     public static StuffToAccess instance;
     
     // I am a singleton
     void Awake() {
         if (instance == null) {
             instance = this;
             DontDestroyOnLoad(instance);
         } else {
             Destroy(this);
         }
     }
     
     public enum TESTING {
             FIRST = 0,
             SECOND,
             THIRD,
             ENUM_COUNT
     };
 
     public string[] strings = new string[(int)TESTING.ENUM_COUNT] {
         "First String",
         "Second String",
         "Third String"
     };
 }
 
 // This is the class that wants to access the one above
 public class ThingThatNeedsAccess : MonoBehaviour {
     
     void Start() {
         
         //Test 1
         Debug.Log( "String contents: " + StuffToAccess.instance.strings[0] );
         
         // Test 2, what I was looking to do (is there a nicer way to achieve this?)
         Debug.Log( "String contents: " + StuffToAccess.instance.strings[ (int)StuffToAccess.TESTING.FIRST ] );
     
     }
 }

However, this gives me the following error: "NullReferenceException: Object reference not set to an instance of an object"

What am I doing wrong here in terms of syntax / design in general? There's probably some better way to do this that I'm not seeing. Thanks for your time.