Adding items doesn't work at demo (F1, F2 etc)

[TheYellowArchitect]

The class FPSDemo:

class_name FPSDemo
extends Node

@export var item_wood : Item
@export var item_stone : Item
@export var item_grass : Item
@export var database : InventoryDatabase

@onready var main_inventory : Inventory

func _ready():
    #main_inventory = InventorySystem.get_inventory_handler().get_inventory(0)
    $"UI/Inventory System UI".setup($"Player/CharacterInventorySystem")

#
#func _process(_delta):
    #if Input.is_action_just_released("add_item_a"):
        #InventorySystem.get_inventory_handler().add_to_inventory(main_inventory, item_wood, 1)
    #if Input.is_action_just_released("remove_item_a"):
        #main_inventory.remove(item_wood, 1)
#
    #if Input.is_action_just_released("add_item_b"):
        #InventorySystem.get_inventory_handler().add_to_inventory(main_inventory, item_stone, 1)
    #if Input.is_action_just_released("remove_item_b"):
        #main_inventory.remove(item_stone, 1)
#
    #if Input.is_action_just_released("add_item_c"):
        #InventorySystem.get_inventory_handler().add_to_inventory(main_inventory, item_grass, 1)
    #if Input.is_action_just_released("remove_item_c"):
        #main_inventory.remove(item_grass, 1)

It should be this:

class_name FPSDemo
extends Node

@export var item_wood : Item
@export var item_stone : Item
@export var item_grass : Item
@export var database : InventoryDatabase

@onready var main_inventory : Inventory = get_node("Player").get_node("CharacterInventorySystem").get_node("InventoryHandler").get_node("Inventory")

func _ready():
    $"UI/Inventory System UI".setup($"Player/CharacterInventorySystem")

#
func _process(_delta):
    if Input.is_action_just_released("add_item_a"):
        main_inventory.add(item_wood, 1)
    if Input.is_action_just_released("remove_item_a"):
        main_inventory.remove(item_wood, 1)

    if Input.is_action_just_released("add_item_b"):
        main_inventory.add(item_stone, 1)
    if Input.is_action_just_released("remove_item_b"):
        main_inventory.remove(item_stone, 1)
#
    if Input.is_action_just_released("add_item_c"):
        main_inventory.add(item_grass, 1)
    if Input.is_action_just_released("remove_item_c"):
        main_inventory.remove(item_grass, 1)

I hate the deep hardcoded reference for main_inventory but I think it's worth it for the demo, since otherwise the left UI messages don't work (thats horrible for a demo!)