"NullReferenceException: Object reference not set to an instance of an object" with instantiate C#

This must be something super simple that I'm missing but I couldn't find it for the life of me.

I have pasted my entire script, but the error is on line 48 when I try to add force to the instantiated object. The object has a rigidbody attached.

 using System.Collections;
 
 public class slimy : MonoBehaviour {
 
     public Rigidbody coin;
     float hp = 10;
     float defence = 1;
     public GameObject[] drops;
     public int[] droprate;
     public int mincoin = 1;
     public int maxcoin = 3;
     public Transform coinpos;
     public float moneyspread = 100;
 
     void OnCollisionEnter2D(Collision2D coll) {
 
         hitarrow ();
         deathcheck ();
     }
     void hitarrow(){
         float initial = playerattack.calculatedmg ("arrow");
         float dmg = initial / defence;
         hp -= dmg;
         Debug.Log ("Damage: " + dmg);
     }
 
     void deathcheck(){
         if (hp <= 0) {
             drop();
             Destroy (gameObject, 0.001f);
         }
     }
     void drop(){
         for(int i = 0; i < (Random.Range (mincoin, maxcoin)); i++){
 
             float coinforce = Random.Range(100f, 350f);
             float coinrot = Random.Range(0f, 360f);
             coinpos.localRotation = Quaternion.Euler(0, 0, coinrot);
             coinpos.position = transform.position;
 /*
             Rigidbody2D shot;
             shot = Instantiate(coin, coinpos.position, coinpos.rotation) as Rigidbody2D;
             shot.velocity = transform.TransformDirection(Vector2.up * coinforce);
 */
             Rigidbody clone;
             clone = Instantiate(coin, transform.position, coinpos.rotation) as Rigidbody;
             clone.velocity = transform.TransformDirection(Vector3.up * 10);
 
         }
     }
 }