NullReferenceException: Object reference not set to an instance of an object gunShooting.Update () (at Assets/gunShooting.cs:26)

error is in the name heres the code:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class gunShooting : MonoBehaviour
{
public Transform Bullet;
public Transform MuzzleFlash;
public Transform Spawn;
public AudioSource Shot;
public AudioSource noAmmo;
public Transform muzzleSpawn;
public Animation reload;
//Gun Stuff
public int bulletsPerMag = 30;
public int usingBulletPerMag;
public int overallAmmo;
public UnityEngine.UI.Text ammoDisplay;
public UnityEngine.UI.Text gunDisplay;
void Start()
{
usingBulletPerMag = bulletsPerMag;
}
void Update()
{
ammoDisplay.text = usingBulletPerMag + “/” + overallAmmo;
if (overallAmmo > 0)
{
if (Input.GetKeyDown(KeyCode.R))
{
//overallAmmo -= bulletsPerMag - usingBulletPerMag;
usingBulletPerMag = bulletsPerMag;
}
}
if (Input.GetMouseButtonDown(0))
{
if (usingBulletPerMag > 0)
{
Shoot();
}
else
{
noAmmo.Play();
}
}
}
void Shoot()
{
Vector3 aimPos = Camera.main.ScreenToWorldPoint(Input.mousePosition);
aimPos.z = 0;

  //Creating the bullet and shooting it
  var pel = Instantiate(Bullet, Spawn.position, Spawn.rotation);
  pel.GetComponent<Rigidbody2D>().AddForce(aimPos.normalized * 8000f);
  //Playing the bullet noise
  Shot.Play();
  //shooting and reloading
  usingBulletPerMag -= 1;

}
}

Hi @Kalnis According the screenshot, ammoDisplay has not been assigned a Text component. As well, noAmmo hasn’t been assigned an AudioSource. As well, the Spawn transform has not been assigned anything. And lastly, the Shot audio source has not been assigned anything. So certainly each of these will cause a null reference exception when used. Hope that helps!