NullReferenceException

I am working on a 3D game and in the scripting part, I am having a NullReference Exception.

Someone please please help me, stuck for a long time.

 

NullReferenceException: Object reference not set to an instance of an object
PhotnDrop () (at Assets/Scripts/Photo.cs:44)
Inventory.RemoveItem (IInventoryItem item) (at Assets/Scripts/Inventory.cs:44)
ItemDropHandler.OnDrop (UnityEngine.EventSystems.PointerEventData eventData) (at Assets/Scripts/ItemDropHandler.cs:27)
UnityEngine.EventSystems.ExecuteEvents.Execute (UnityEngine.EventSystems.IDropHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs:85)
UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction`1[T1] functor) (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/EventSystem/ExecuteEvents.cs:261)
UnityEngine.EventSystems.EventSystem:Update()

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Photo : InventoryItemBase
6. {
7.     public GameObject replace;
8.  
9.     public Inventory inventory;
10.  
11.     public HUD Hud;
12.     // Start is called before the first frame update
13.     public override string Name
14.     {
15.         get
16.         {
17.             return "Photo";
18.         }
19.     }
20.  
21.     public override void OnDrop()
22.     {
23.         RaycastHit hit = new RaycastHit();
24.         Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
25.         replace = GameObject.FindGameObjectWithTag("replace");
26.         if (Physics.Raycast(ray, out hit, 1000))
27.         {
28.             //TODO item drop functionality on a fixed wall
29.             gameObject.SetActive(true);
30.             //gameObject.transform.position = hit.point;
31.             //Destroy(replace.gameObject);
32.             if (hit.collider.gameObject.CompareTag("replace"))
33.             {
34.                // gameObject.SetActive(true);
35.                 gameObject.transform.position = replace.gameObject.transform.position;
36.                 gameObject.transform.rotation = replace.gameObject.transform.rotation;
37.                 Destroy(replace.gameObject);
38.              
39.             }
40.             else
41.             {
42.                 gameObject.SetActive(false);
43.                 IInventoryItem _item = gameObject.GetComponent<IInventoryItem>();
44.                 inventory.AddItem(_item);
45.                 _item.OnPickup();
46.                 Hud.CloseMessagePanel();
47.             }
48.          
49.         }
50.     }
51. }

 

You should put the code up you're having trouble with

 

I am having trouble with this code at line number 44

 

Code (CSharp):

1. inventory.AddItem(_item);

I'm guessing _item doesn't exist when you're trying to add it because:

Code (CSharp):

1. IInventoryItem _item = gameObject.GetComponent<IInventoryItem>();

can't GetComponent because it's not there. Null Reference always means GetComponent can't find the thing it's meant to be getting and returning this error. IInventoryItem isn't declred in this class so I don't know what that's doing.
If you make and IInventoryItem public at the start of your code, you will be able to see in the inspector which is the problem.