how to detect wich item i have in my inevntory

i found a video on youtube wich showed me how to make a inventory system. I made some changes but now i dont understand how to check wich items are in my inventory. In my ItemObj scrip i tried the method

"if (this.GetComponent().sprite.name == "Weapon")"

but if i try to use something like a campfire it gets a null refrence exception. Can somebody help me to find out how to detect wich items i have in my inventory?

temDataBase script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
  
 public class ItemDataBase : MonoBehaviour
 {
     public List<Item> items = new List<Item>();
 
     void Awake()
     {
         GetItemByID();
     }
 
     
 
     void GetItemByID()
     {
         items.Add(new Item("Glock", "Waffe", "Hoffentlich", 0));
         items.Add(new Item("M4A1", "Ein 8 Kaliber Gewehr", "Weapon", 1));
     }
 
     public Item GetItemByID(int id)
     {
         foreach (Item itm in items)
         {
             if(itm.itemId == id)
             {
                 return itm;
             }
         }
 
         
         return null;
         
     }
 }

Item scirpt:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
  
 [System.Serializable]
 public class Item {
     public int itemId;
     public string itemDescription;
     public Sprite itemSprite;
     public string itemName;
     public string itemSpriteName;
  
     public Item(string name, string description, string spriteName, int id)
     {
         itemName = name;
         itemDescription = description;
         itemSpriteName = spriteName;
         itemSprite = Resources.Load<Sprite>("ItemIcons/" + spriteName);
         itemId = id;
         
     }
 
     public Item()
     {
 
     }
  
     
 }

Inventory script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class Inventory : MonoBehaviour
 {
 
     public int slotAmount = 11;
     public GameObject slotPrefab;
     public GameObject slotParent;
     public GameObject InventoryObject;
     public GameObject itemPrefab;
 
     private MouseLook mouseLook;
 
     private ToolTip tooltip;
 
     public List<GameObject> slots = new List<GameObject>();
     
 
     private ItemDataBase itemDatabase;
 
     public KeyCode inventorykey = KeyCode.Tab;
 
     public bool isShown = false;
     
 
     // Start is called before the first frame update
     void Start()
     {
 
         CreateSlots(slotAmount);
 
         mouseLook = GameObject.FindObjectOfType<MouseLook>();
 
         itemDatabase = GameObject.FindGameObjectWithTag("ItemDataBase").GetComponent<ItemDataBase>();
 
         tooltip = GameObject.FindGameObjectWithTag("Tooltip").GetComponent<ToolTip>();
 
     }
 
 
     void Update()
     {
         
         if (Input.GetKeyDown(inventorykey))
         {
             isShown = !isShown;
 
             if(isShown == true)
             {
                 Cursor.visible = true;
                 tooltip.ToggleTooltip(false);
                 Cursor.lockState = CursorLockMode.None;
                 mouseLook.mouseSensitivity = 0f;
 
             }
             else if (isShown == false)
             {
                 
                 Cursor.lockState = CursorLockMode.Locked;
                 mouseLook.mouseSensitivity = 900f;
                 Cursor.visible = false;
             }
 
         }
         if(isShown == true)
         {
             InventoryObject.SetActive(true);
 
         }
         else if(isShown == false)
         {
             InventoryObject.SetActive(false);
 
 
         }
     }
     // Update is called once per frame
     void CreateSlots(int slotAmount)
     {
         for (int i = 0; i < slotAmount; i++)
         {
             slots.Add(Instantiate(slotPrefab));
             slots[i].transform.SetParent(slotParent.transform);
         }
     }
 
     public void AddItem(int id)
     {
         Item itemAdd = itemDatabase.GetItemByID(id);
         for (int i = 0; i < slots.Count; i++)
         {
             if(slots[i].transform.childCount <= 0)
             {
                 GameObject itemInstance = Instantiate(itemPrefab);
                 itemInstance.transform.SetParent(slots[i].transform);
                 itemInstance.transform.localPosition = Vector2.zero;
                 itemInstance.GetComponent<Image>().sprite = itemAdd.itemSprite;
                 break;
             }
 
            
         }
         
     }
 
    
 }

ItemObj script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.EventSystems;
 using UnityEngine.UI;
 
 public class ItemObj : MonoBehaviour, IDragHandler, IBeginDragHandler, IEndDragHandler, IPointerEnterHandler, IPointerExitHandler
 {
     private Transform startParent;
 
     private CanvasGroup canvasGroup;
 
     private Campfire campfire;
 
     private Item item;
 
     private PickUp pickUp;
  
     public Inventory inventory;
 
     private ItemDataBase itemDataBase;
 
     private ToolTipButton toolTipB;
 
     private ToolTip tooltip;
     private ToolTipButton toolTipButton1;
     private ToolTipButton toolTipButton2;
 
     private Food foodItem;
     private PlayerMovement playerMovement;
     private Interact interact;
 
 
     private bool inItem = false;
 
     private void Start()
     {
         interact = GameObject.FindObjectOfType<Interact>();
         foodItem = GameObject.FindObjectOfType<Food>();
         playerMovement = GameObject.FindObjectOfType<PlayerMovement>();
         inventory = GameObject.FindObjectOfType<Inventory>();
         canvasGroup = GetComponent<CanvasGroup>();
         toolTipB = GameObject.FindObjectOfType<ToolTipButton>();
         pickUp = GameObject.FindObjectOfType<PickUp>();
         
 
         tooltip = GameObject.FindGameObjectWithTag("Tooltip").GetComponent<ToolTip>();
         toolTipButton1 = GameObject.FindGameObjectWithTag("TooltipButton1").GetComponent<ToolTipButton>();
         toolTipButton2 = GameObject.FindGameObjectWithTag("TooltipButton2").GetComponent<ToolTipButton>();
 
 
         startParent = transform.parent;
     }
 
     private void Update()
     {
 
         if (Input.GetKeyDown(KeyCode.Mouse1) && inItem == true)
         {
             tooltip.ToggleTooltip(true, Input.mousePosition);
 
             toolTipButton1.actionMethod = UseItemButton;
 
             toolTipButton2.actionMethod = DropViaItemButton;
         }
 
         Ray ray = Camera.main.ScreenPointToRay(new Vector2(Screen.width / 2, Screen.height / 2));
         RaycastHit hitInfo;
         if (Physics.Raycast(ray, out hitInfo))
         {
             if (hitInfo.collider.tag == "Campfire")
             {
                 if (Input.GetKeyDown(KeyCode.E))
                 {
                     if (this.GetComponent<Image>().sprite.name == "Weapon")
                     {
                         Destroy(gameObject);
                         campfire = hitInfo.collider.GetComponent<Campfire>();
                         inventory.AddItem(0);
                         
                     }
                 }
 
             }
         }
 
     }
 
     private void UseItemButton()
     {
         if (this.GetComponent<Image>().sprite.name == "Hoffentlich")
         {
             Debug.Log("you used it");
 
             useItemTwo();
         }
 
         if (this.GetComponent<Image>().sprite.name == "Weapon")
         {         
             Debug.Log("you used it");
 
             useItem();
         }
     }
 
     private void DropViaItemButton()
     {
         if (this.GetComponent<Image>().sprite.name == "Hoffentlich")
         {
             DropItem();
 
             Debug.Log("You dropped your item!");
         }
 
         if (this.GetComponent<Image>().sprite.name == "Weapon")
         {
             DropItem();
 
             Debug.Log("You dropped your item!");
         }
     }
 
 
     void useItem()
     {
         interact.TestHunger2();
 
         Destroy(gameObject);
     }
 
     void useItemTwo()
     {
         interact.TestHunger();
 
         Destroy(gameObject);
     }
 
 
 
     void DropItem()
     {
         Destroy(gameObject);
         
     }
 
 
 
 
 
     public void OnBeginDrag(PointerEventData eventData)
     {       
         transform.position = eventData.position;
 
         transform.SetParent(transform.parent.parent);
 
         canvasGroup.blocksRaycasts = false;
     }
 
     public void OnDrag(PointerEventData eventData)
     {
         transform.position = eventData.position;
     }
 
     public void OnEndDrag(PointerEventData eventData)
     {
         GetSlotInfo();
 
         canvasGroup.blocksRaycasts = true;
     }
 
 
     private void GetSlotInfo()
     {
         GameObject[] slots = GameObject.FindGameObjectsWithTag("Slot");
 
         foreach (var slot in slots)
         {
             if(slot.GetComponent<Slot>().isSelected == true)
             {
                 if(slot.transform.childCount > 0)
                 {
                     ItemObj otherItem = slot.transform.GetChild(0).GetComponent<ItemObj>();
 
                     Transform otherItemParent = otherItem.startParent;
                     otherItem.startParent = startParent;
                     startParent = otherItemParent;
 
                     otherItem.transform.SetParent(otherItem.startParent);
                     otherItem.transform.localPosition = Vector2.zero;
                 }
                 else
                 {
 
                     startParent = slot.transform;
 
                 }
                
                 break;
             }
         }
 
         transform.SetParent(startParent);
         transform.localPosition = Vector2.zero;
     }
 
     public void OnPointerEnter(PointerEventData eventData)
     {
         inItem = true;
     }
 
     public void OnPointerExit(PointerEventData eventData)
     {
         inItem = false;
     }
 }
 

i would be really gratefull if somebody could help me