NullReferenceException Error

I get this error when I approach the object in game:

NullReferenceException: Object reference not set to an instance of an object TerminalHack.OnTriggerStay (UnityEngine.Collider other) (at Assets/Scripts/Modules/TerminalHack.js:28)

 function OnTriggerStay (other : Collider) {
             
     if (other.gameObject.tag == "Player") 

I changed something in the prefab now it seems to have broken a link. I don't understand what has to be initialized. What to do? TIA