Getting NullReference when calling Instantiate from another script

Hi All – Need the help, please!

New to unity and I have run into the dreaded

“NullReferenceException: Object reference not set to an instance of an object

What I am trying to do is instantiate a Gameobject within an array from another script. Code snip it below

code is in C# (ScriptGame)

 using UnityEngine;
 using System.Collections;
 public class ScriptGame : MonoBehaviour {
 
 public GameObject [] cube;
 public float playTime       = 0.0f;            
 public float delayTime        = 0.0f;
 public float delayAmount    = 0.0f;
 public bool timeActive        = true;            
 private float xOriginalpos;    
 private float xOffsetpos        = -3.8f;
 
 // Update is called once per frame
 void Update (){
     
 if (timeActive)
     {
     playTime = Time.time;                        
     }
     
     if (playTime > delayTime)
     {
         delayAmount = Random.Range(4,8);
         delayTime = Time.time + delayAmount;
             
         xOriginalpos = Random.Range(0,10);
         spawn ((xOffsetpos + xOriginalpos) , 19.0f);
         Debug.Log ("Delayed of " + delayAmount + "Seconds");
     }
 }
 
 public void spawn(float x, float y){
 
 Instantiate (cube[Random.Range(0, cube.Length)],new Vector3(x, y, 9.0f), Quaternion.identity);
 }
 
 }
 

Then from the other script (scriptBlock.cs) I try call "spawn" after confirming the correct Gameobject was hit using RayCast.

     public void changecolor (){
         if (Input.GetMouseButtonDown(0)){
             Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
             if (Physics.Raycast(ray, out colorHit, rayDistance)){
             if (((colorHit.transform.tag == "BLUE") || (colorHit.transform.tag == "CYAN" )) && (colorHit.transform.position.y > 2.68f)){
                 //Debug.Log ("Hitcolor");
                 
                 ScriptGame other;
                 other = gameObject.GetComponent("ScriptGame") as ScriptGame;
                 other.spawn(3.8f, 19.0f);
                     
                 }
             }
     
         }
     }

When I click on the object attached to the above script (scriptBlock.cs)) I get

NullReferenceException: Object reference not set to an instance of an object scriptBlock.changecolor () (at Assets/Scripts/scriptBlock.cs:131) scriptBlock.Update () (at Assets/Scripts/scriptBlock.cs:32)”

the error points to the following line

other.spawn(3.8f, 19.0f);

I am not sure how to fault find this issue. I think it has something to do with the cube array (but it is populated with prefabs correctly)

All help appreciated

Thank you