Confused as to why I'm getting a NullReference Exception

I have no clue as to why I'm getting a NullReference exception, since I did the same code in a different script and it works perfectly. Here's the full error: NullReferenceException: Object reference not set to an instance of an object TurretControl.Shoot (Int32 seconds) (at Assets/Custom/Scripts/TurretControl.cs:50) TurretControl.Update () (at Assets/Custom/Scripts/TurretControl.cs:34)

And here's the code of TurretControl.cs:

 using UnityEngine;
 using System.Collections;
 
 public class TurretControl : MonoBehaviour
 {
     public Transform target;
     public Transform bulletPrefab;
     public float viewDistance;
     public float damp;
     public float bulletSpeed;
     private int savedSeconds;
     
     void Start()
     {
         
     }
     
     void Update()
     {
         if(target)
         {
             float distance = Vector3.Distance(transform.position, target.position);
             Quaternion rotate = Quaternion.LookRotation(target.position - transform.position);
             
             if(distance <= viewDistance)
             {
                 transform.rotation = Quaternion.Slerp(transform.rotation, rotate, Time.deltaTime * damp);
                 
                 int seconds = (int)Time.time;
                 int odd = (seconds % 2);
                 
                 if(odd == 0)
                 {
                     Shoot(seconds);
                 }
             }
         }
     }
     
     void Shoot(int seconds)
     {
         if(seconds != savedSeconds)
         {
             savedSeconds = seconds;
             
             GameObject bullet = Instantiate(bulletPrefab,
                             GameObject.Find("turretFireBallSpawn").transform.position,
                             Quaternion.identity) as GameObject;
 
             bullet.rigidbody.AddForce(transform.forward * (bulletSpeed * 1000));
         }
     }
 }

And this is line 50: bullet.rigidbody.AddForce(transform.forward * (bulletSpeed * 1000));