'Place a block using a method in another script [duplicate]

I'm trying to place a block in the game that i am making, I'm trying to call a method from another script and gameObject.

The code i call:

  {
      GameObject instance = Instantiate(tilesprite, new Vector2(x - 100f, y - 33.675f), Quaternion.identity) as GameObject;
      instance.transform.SetParent(this.transform);
      //grid[x, y] = (int)this.transform.position.x, (int)this.transform.position.y];

  }

The code that i call this from:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class CursorsCursorFollow : MonoBehaviour
{
    public Transform target;
    public float smoothSpeed = 0.125f;
    public Vector3 offset;
    public RnadomGeneration2 terrain;
    public bool place;

    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        Vector3 desiredPosition = target.position + offset;
        Vector3 smoothedPosition = Vector3.Lerp(transform.position, desiredPosition, 1);// smoothSpeed);
        transform.position = smoothedPosition;
        
    }

    void FixedUpdate()
    {
        Vector3 mousePos = Input.mousePosition;
        //place = Input.GetMouseButtonDown(0);
        if (Input.GetMouseButtonDown(0))
        {
            GameManager.instance.what_tile = 3;

            GameObject tilesprite;
            if (GameManager.instance.what_tile == 0)
            {
                tilesprite = null;
            }
            else if (GameManager.instance.what_tile == 1)
            {
                tilesprite = GameManager.instance.dirt;
            }
            else if (GameManager.instance.what_tile == 2)
            {
                tilesprite = GameManager.instance.grass;
            }
            else if (GameManager.instance.what_tile == 3)
            {
                tilesprite = GameManager.instance.stone;
            }
            else
            {
                tilesprite = null;
            }
            //if (terrain != null && tilesprite != null)
            //{
                terrain.PlaceTile(tilesprite, Mathf.RoundToInt(mousePos.x), Mathf.RoundToInt(mousePos.y)); <line 59>
            //}
        }
    }
}

Get the error: NullReferenceException: Object reference not set to an instance of an object CursorsCursorFollow.FixedUpdate () (at Assets/Scripts/CursorsCursorFollow.cs:59)

What is wrong with my code?

c++sharpunity3dscript


Solution 1:[1]

You are not mentioning what row you are getting the error message at which makes it harder. But a null reference is usually really easy to solve, it means you haven't declared something that it is trying to run on the row that gives the error. Possibly the terrain, tilssprite or the mousePos.

Solution 2:[2]

@Sven_Viking has provided the answer.

if( terrain != null && tilesprite != null )

This code helped as it created a clone, and it made sure that a null wasn't passed through the variable.

Sources

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Source: Stack Overflow

Solution Source
Solution 1 eligolf
Solution 2

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