I can no longer place cactus on the playing field

[LittleHouse]

Everything was working fine. If I place a cactus in the scene before I hit play, it will switch back and forth from idle to attack, but if I try to place a cactus I get this error:

NullReferenceException: Object reference not set to an instance of an object
DefenderSpawner.AttemptToPlaceDefenderAt (UnityEngine.Vector2 gridPos) (at Assets/Scripts/DefenderSpawner.cs:33)
DefenderSpawner.OnMouseDown () (at Assets/Scripts/DefenderSpawner.cs:23)
UnityEngine.SendMouseEvents:DoSendMouseEvents(Int32)

I have no trouble placing a trophy.
Here is the Defender Spawner Script:

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

public class DefenderSpawner : MonoBehaviour
{
    Defender defender;

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

    // Update is called once per frame
    void Update()
    {
      
    }

    void OnMouseDown()
    {
        AttemptToPlaceDefenderAt(GetSquareClicked());
    }
    public void SetSelectedDefender(Defender defendertoSelect)
    {
        defender = defendertoSelect;
    }

    private void AttemptToPlaceDefenderAt(Vector2 gridPos)
    {
        var StarDisplay = FindObjectOfType<StarDisplay>();
        int defenderCost = defender.GetStarCost();

        if (StarDisplay.HaveEnoughStars(defenderCost))
        {
            SpawnDefender(gridPos);
            StarDisplay.SpendStars(defenderCost);
        }
    }

    private Vector2 GetSquareClicked()
    {
        Vector2 clickPos = new Vector2(Input.mousePosition.x, Input.mousePosition.y);
        Vector2 worldPos = Camera.main.ScreenToWorldPoint(clickPos);
        Vector2 gridPos = SnapToGrid(worldPos);
        return gridPos;
    }

    private Vector2 SnapToGrid(Vector2 rawWorldPos)
    {
        float newX = Mathf.RoundToInt(rawWorldPos.x);
        float newY = Mathf.RoundToInt(rawWorldPos.y);
        return new Vector2(newX, newY);
    }
    private void SpawnDefender(Vector2 roundedPos)
    {
       Defender newDefender = Instantiate(defender, roundedPos, transform.rotation) as Defender;
    }
        
         
    
}

I must have done something to break it, but I can’t find it.

[Patricia]

Hello LittleHouse,
not sure if that is it, but are your costs higher than the amount of stars you have for the cactus?

[LittleHouse]

Good thought Patricia, but I had set the stars to 1000, so that isn’t it.

[Patricia]

The other thing which could maybe be it is that you didn’t attach the prefab in the inspector - Defender Button Script.
Your code does look fine compared to Rick’s, even if there will be more stuff in the final one. So my guess is that there is something in the inspector.
Anyways, I hope you figure it out:)

[LittleHouse]

Thanks, that was it. I think what happened was that I had put an instance of the cactus in the inspector instead of the prefab and when I deleted the instance (like Rick did in the video), it broke the cactus.

[Patricia]

You are welcome.