Trying to save and load duplicated scriptable object items for inventory:

Unity Engine
1

I have tried adding a save system:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
public class MainInventory : MonoBehaviour
{
    public WorldScript world;

    [System.Serializable]
    public class MainInventoryStorage
    {
        public List<InventorySlotData> inventorySlotsData = new List<InventorySlotData>();
    }
    public MainInventoryStorage storage;

    public List<InventorySlot> inventorySlots = new List<InventorySlot>();

    public Item testItem;

    public void Start ()
    {
        updateInventoryUI();
        addTestItem();
    }

    private void Update()
    {
        if (Input.GetKeyDown(KeyCode.P))
        {
            saveInventory();
        } else if (Input.GetKeyDown(KeyCode.L))
        {
            loadInventory();
        }
    }

    public void updateInventoryUI ()
    {
        for (int i = 0; i < inventorySlots.Count; i++)
        {
            inventorySlots[i].updateSlot(world.cloneItem(storage.inventorySlotsData[i].storedItem));
        }
    }

    public void addTestItem()
    {
        testItem = world.cloneItem(world.gameItems[0]);
        storage.inventorySlotsData[0].storedItem = testItem;
        storage.inventorySlotsData[0].storedItem.itemName = "Test";
        updateInventoryUI();
    }

    public void saveInventory ()
    {
        string testSave = JsonUtility.ToJson(storage);
        PlayerPrefs.SetString("storage", testSave);
    }

    public void loadInventory ()
    {
        storage = JsonUtility.FromJson<MainInventoryStorage>(PlayerPrefs.GetString("storage"));
        updateInventoryUI();
    }
}

but when I hit L it gives error:

Argument Exception: The object you want to instantiate is null

Here are the rest of the scripts:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
public class WorldScript : MonoBehaviour
{

    public List<Item> gameItems = new List<Item>();

    public Item cloneItem (Item toClone)
    {
        Item clone = Instantiate<Item>(toClone);
        return clone;
    }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
[CreateAssetMenu(fileName = "Item", menuName = "ScriptableObjects/Item", order = 1)]
public class Item : ScriptableObject
{
    public string itemName, itemDescription, itemID;
    public bool stackable = false;
    public int stackSize, maxStackSize;
}

can someone please tell me what I am doing wrong?

2

is json valid? u can use json lint to check.