Unity giving me an error when it shouldn't

Ok so ive been following a tutorial on how to make inventorys by inScope studios, anyways I got to about an hour in the video, and I followed step by step, but unity gives me an error when I attempt to pick an item up. In his video he doesnt get the error and is able to pick the item up perfectly, So i spent 4+ hours going back and through my code and his code and I nailed down every line exactly but I still get the error. Heres the error:

"NullReferenceException: Object reference not set to an instance of an object
Slot.get_IsEmpty () (at Assets/Scripting/Slot.cs:18)
Inventory.placeEmpty (.ItemScript item) (at Assets/Scripting/Inventory.cs:101)
Inventory.AddItem (.ItemScript item) (at Assets/Scripting/Inventory.cs:87)
KeyBinding.checkPickup () (at Assets/Scripting/KeyBinding.cs:75)
KeyBinding.Update () (at Assets/Scripting/KeyBinding.cs:31)"

And it targets this script specifically:

Code (CSharp):

1. using UnityEngine;
2. using System.Collections;
3. using System.Collections.Generic;
4. using UnityEngine.UI;
5.  
6. public class Slot : MonoBehaviour {
7.  
8.     private Stack<ItemScript> items;
9.  
10.     public Text stackTxt;
11.  
12.     public Sprite SlotEmpty;
13.  
14.     public Sprite SlotHighlight;
15.  
16.     public bool IsEmpty
17.     {
18.         get { return items.Count == 0; }      
19.     }
20.  
21.     void start()
22.     {
23.        
24.  
25.         items = new Stack<ItemScript>();
26.  
27.         RectTransform slotRect = GetComponent<RectTransform>();
28.         RectTransform txtRect = GetComponent<RectTransform>();
29.  
30.         int txtScaleFactor = (int)(slotRect.sizeDelta.x * 0.60); //calc scale factor
31.         stackTxt.resizeTextMaxSize = txtScaleFactor; //set max scale factor
32.         stackTxt.resizeTextMinSize = txtScaleFactor; //set min scale factor
33.  
34.  
35.         txtRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Vertical, slotRect.sizeDelta.y);
36.         txtRect.SetSizeWithCurrentAnchors(RectTransform.Axis.Horizontal, slotRect.sizeDelta.x);
37.        
38.  
39.     }
40.  
41.     private void ChangeSprite(Sprite neutral, Sprite highlight)
42.     {
43.  
44.  
45.         GetComponent<Image>().sprite = neutral;
46.  
47.         SpriteState st = new SpriteState();
48.         st.highlightedSprite = highlight;
49.         st.pressedSprite = neutral;
50.  
51.         GetComponent<Button>().spriteState = st;
52.  
53.  
54.  
55.     }
56.     void Update()
57.     {
58.  
59.     }
60.  
61.     public void AddItem(ItemScript item)
62.     {
63.  
64.  
65.         items.Push(item);
66.  
67.         if (items.Count > 1) //Update stack number if > 1
68.         {
69.  
70.             stackTxt.text = items.Count.ToString(); //writes the amount of items and converts to str
71.  
72.         }
73.  
74.         ChangeSprite(item.spriteNeutral, item.spriteHighlighted); //change sprite from slot to whatever we add
75.  
76.  
77.     }
78.  
79. }
80.  

Note that
public bool IsEmpty
{
get { return items.Count == 0; }
}
is where the problem is apparently coming from.
I get the error whenever I collide with the object im trying to pick up, and i've even tried picking it up with a raycast, and I still receive the exact same error.


P.S (Another problem im encountering is whenever I reboot this unity project my vertical axis on my FPS controller gets locked and I cant look up or down, my only work around was to delete the controller and put a new one in, even so its still incredibly annoying.)

 

Start

not

start

c# is case sensitive

 

ARE YOU SERIOUS RIGHT NOW IM LITERALLY GOING TO DRINK BLEACH I SPENT 4 HOURS TRYING TO FIX THAT

Ps thanks fam u just solved it

 

fresh set of eyes

 

Just a friendly piece of advice. This tactic is not known to improve programming ability.