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

Hey there, so the title says the problem I have, I tried everything I could possible imagine and see arround other awnsers and topics, with no luck to fix my problem.

So here's my code (not all of it but where it says I have the problem)

 public class SlotInv {
 
     public int[] ItemIndex;
     public int[] ItemAmount;
 
 public SlotInv Inventory;
 
 void Awake () {
 
     Inventory.ItemIndex = new int[40];
     Inventory.ItemAmount = new int[40];

The problem is on the Awake function I think, so I hope someone can help me.

Thanks in advance!