It show that you can not access the gameobject it already destroyed

in this i dont know but it show that you can not access the gameobject it already destroyed

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

public class SpawnManager : MonoBehaviour
{
    public GameObject[] animalPrefabs;
    private float spawnRangeX = 20;
    private float spawnPosZ = 20;
    private float spwanDelay = 2;
    private float spawnInterval= 1.5f;
    // Start is called before the first frame update
    void Start()
    {
        InvokeRepeating("SpawnRandomAnimal",spwanDelay,spawnInterval);
        
    }

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

        
    }
    void SpawnRandomAnimal()
    {
        int animalIndex = Random.Range(0, animalPrefabs.Length);
        Vector3 spawnPos = new Vector3(Random.Range(-spawnRangeX, spawnRangeX), 0, spawnPosZ);
        Instantiate(animalPrefabs[animalIndex], spawnPos, animalPrefabs[animalIndex].transform.rotation);
    }
}