Object refrence not set to an instance of an object

For some reason, the Unity console shows an "Object reference not set to an instance of an object error" when I run this line of code:

Debug.Log("MESH IS " + CharacterChange.instance.Player);

Why am I getting this error?

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

public class CharacterChange : MonoBehaviour
{
    public static CharacterChange instance;

    public static GameObject player1dub;
    public GameObject Player;
    public GameObject orangeShown;
    public GameObject grapesShown;
    public GameObject appleShown;
    public GameObject bananaShown;
    public int num;
    public Transform playerTransform;
    public Transform orangeTransform;
    public Transform grapesTransform;
    public Transform appleTransform;
    public Transform bananaTransform;
    public Transform orangeHitPoint;
    public Transform grapesHitPoint;
    public Transform remyHitPoint;
    public Transform appleHitPoint;
    public Transform bananaHitPoint;
    public Transform secondplayerhit;
    public Transform orangeCameraMovement;
    public Transform grapesCameraMovement;
    public Transform remyCameraMovement;
    public Transform appleCameraMovement;
    public Transform bananaCameraMovement;
    public Transform secondplayercamera;
    PlayerMotion playerMotionScript;
    CameraManager cameraManagerScript;
    Gun gunScript;
    Animator myAnimator;
    Timer timerscript;
    ScalingOfModels scalingScript;
    AiSensor sensorScript;
    //public SpawnerCharacter characterSpawn;

    public bool scaleBool;
    public bool remyScaleBool;
    public Vector3 endScale;
    public Vector3 startScale;
    public float timeDuration;
    public float elapsedTime;

    void Start()
    {
        playerMotionScript = GetComponentInParent<PlayerMotion>();
        cameraManagerScript = FindObjectOfType<CameraManager>();
        gunScript = FindObjectOfType<Gun>();
        scalingScript = GetComponent<ScalingOfModels>();
        myAnimator = GetComponent<Animator>();
        timerscript = FindObjectOfType<Timer>();
        sensorScript = GetComponent<AiSensor>();
        startScale = playerMotionScript.selectedPlayer.transform.localScale;
    }

    public IEnumerator RemyChangeEnumerator()
    {
        if (playerMotionScript.selectedPlayer != Player)
        {
            playerMotionScript.selectedPlayer.SetActive(false);
            elapsedTime += Time.deltaTime;
            float complete = elapsedTime / timeDuration;
            playerMotionScript.selectedPlayer.transform.localScale = Vector3.Lerp(endScale, startScale, complete);
            playerTransform.position = playerMotionScript.selectedPlayer.transform.position;
            Player.SetActive(true);
            playerMotionScript.allHitPoints = remyHitPoint;
            playerMotionScript.selectedPlayer = Player;
            playerMotionScript.HandlePlayerChange();
            cameraManagerScript.SetCameraMovement(remyCameraMovement);
            yield return null;
        }
    }

    private void OnTriggerEnter(Collider other)
    {
        Destroy(other.gameObject);

        if (other.gameObject.tag == "OrangeCollision" && playerMotionScript.selectedPlayer != orangeShown)
        {
            ChangeCharacter(orangeShown, orangeTransform, orangeHitPoint, orangeCameraMovement);
        }
        else if (other.gameObject.tag == "GrapesCollision" && playerMotionScript.selectedPlayer != grapesShown)
        {
            ChangeCharacter(grapesShown, grapesTransform, grapesHitPoint, grapesCameraMovement);
        }
        else if (other.gameObject.tag == "AppleCollision" && playerMotionScript.selectedPlayer != appleShown)
        {
            ChangeCharacter(appleShown, appleTransform, appleHitPoint, appleCameraMovement);
        }
        else if (other.gameObject.tag == "BananaCollision" && playerMotionScript.selectedPlayer != bananaShown)
        {
            ChangeCharacter(bananaShown, bananaTransform, bananaHitPoint, bananaCameraMovement);
        }
    }

    private void ChangeCharacter(GameObject newCharacter, Transform newTransform, Transform newHitPoint, Transform newCameraMovement)
    {
        playerMotionScript.selectedPlayer.SetActive(false);
        elapsedTime += Time.deltaTime;
        float complete = elapsedTime / timeDuration;
        playerMotionScript.selectedPlayer.transform.localScale = Vector3.Lerp(endScale, startScale, complete);

        newTransform.position = playerMotionScript.selectedPlayer.transform.position;
        newCharacter.SetActive(true);

        playerMotionScript.allHitPoints = newHitPoint;
        playerMotionScript.selectedPlayer = newCharacter;
        playerMotionScript.HandlePlayerChange();

        cameraManagerScript.SetCameraMovement(newCameraMovement);

        timerscript.linewait = 5;
        timerscript.timerBar.fillAmount = 1;

        newCharacter.GetComponent<ScalingOfModels>().scale = true;
    }
}

The above is my character change script, and below is my select button script:

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

public class SelectButton : MonoBehaviour
{
    public Button selectButton;
    public GameObject[] characterPrefabs;
    public CharactersManager managerScript;
    // Start is called before the first frame update
    void Start()
    {
    }

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

    public void CharactersSelect()
    {
        if (managerScript.imageCollection[0])
        {
            Debug.Log("MESH IS " + CharacterChange.instance.Player);
        }
    }
}