NullReferenceException: Object reference not set to an instance of an object

I am getting the following error in my script and i dont know why here is the script

NullReferenceException: Object reference not set to an instance of an object
Coin.OnTriggerEnter2D (UnityEngine.Collider2D other) (at Assets/Coin.js:11)

#pragma strict

public var Money : MenuShopSystem ;
function Start () {

}

 function OnTriggerEnter2D (other: Collider2D)
 {
   Debug.Log ("Touch");
   Money.Money += 100;
   Destroy(this.gameObject);
 
 }

Sounds like the Money field in the inspector isn’t linked to anything, or generally no script is setting the Money variable to anything.

Select your game object that contains this script, find the Money field in the inspector and drag and drop your game object that contains the MenuShopSystem script.