Amount is an inherent property of all item pickups

levels/debug_level/debug_level.tscn

@@ -383,6 +383,7 @@ spawn_turns = 2
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 2.54289, 1.1, 4.28708)
 script = ExtResource("8_5kaye")
 item = ExtResource("12_tj0lh")
+amount = 5
 spawn_on_ready = true
 spawn_turns = 1
 
@@ -390,6 +391,7 @@ spawn_turns = 1
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 8.02452, 1.1, 5.12384)
 script = ExtResource("8_5kaye")
 item = ExtResource("15_ir4ss")
+amount = 5
 spawn_on_ready = true
 spawn_turns = 1
 
@@ -425,6 +427,7 @@ transform = Transform3D(-0.734269, 0.305072, -0.606448, 0, 0.893336, 0.44939, 0.
 transform = Transform3D(0.909686, 0, 0.415297, 0, 1, 0, -0.415297, 0, 0.909686, 537.767, 5.1, 452.434)
 script = ExtResource("8_5kaye")
 item = ExtResource("12_tj0lh")
+amount = -1
 spawn_on_ready = true
 spawn_turns = 1
 
@@ -447,6 +450,7 @@ transform = Transform3D(-4.37114e-08, 0, -1, 0, 1, 0, 1, 0, -4.37114e-08, 0, -0.
 transform = Transform3D(1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 25.5, 0)
 script = ExtResource("8_5kaye")
 item = ExtResource("15_ir4ss")
+amount = 3
 spawn_on_ready = true
 spawn_turns = 2
 

src/items/extra_ball/brick_item.tscn

@@ -98,7 +98,7 @@ _data = {
 [node name="BrickItem" instance=ExtResource("1_gflnq")]
 script = ExtResource("2_vfkkm")
 ball_type = 3
-amount = -1
+amount = 0
 
 [node name="Pivot" parent="Pivot/Octahedron/ItemMeshContainer" index="0"]
 transform = Transform3D(0.99863, 0.052336, 0, -0.052336, 0.99863, 0, 0, 0, 1, 0, 0, 0)

src/items/extra_ball/extra_ball.gd

@@ -1,13 +1,10 @@
 class_name ExtraBall extends Item
 ## Item which grants extra balls when picked up.
+## Amount values < 0 will instead grant the player unlimited ammunition of this type.
 
 ## Type of ball which will be replenished.
 @export var ball_type: GameBall.Type
 
-## Amount to grant.
-## Values < 0 will instead grant the player unlimited ammunition of this type.
-@export var amount: int = -1
-
 
 func _collect(player: WorldPlayer) -> void:
 	if amount < 0:

src/items/item/item.gd

@@ -3,6 +3,10 @@ class_name Item extends Node3D
 
 signal on_collect(player: WorldPlayer)
 
+## Quantity of the underlying item this pick-up will grant when collected.
+## What this actually means is implementation-dependent.
+@export var amount: int = 1
+
 @onready var explosion_player: AnimationPlayer = %ExplosionPlayer
 
 

src/items/item_spawner.gd

@@ -8,6 +8,9 @@ const POP_IN_TIME := 1.618
 ## Item to be spawned
 @export var item: PackedScene
 
+## Quantity of the given item to include in the spawned item pickup, where applicable.
+@export var amount: int = 1
+
 @export_category("Spawn Conditions")
 ## Spawn an item when the tree is loaded.
 @export var spawn_on_ready: bool = false
@@ -43,6 +46,7 @@ func _ready() -> void:
 ## This can be called manually if an item needs complex spawning logic.
 func spawn() -> void:
 	var instance: Item = item.instantiate()
+	instance.amount = amount
 	instance.on_collect.connect(_on_item_collected)
 	add_child(instance)
 

src/player/world_player.gd

@@ -70,7 +70,7 @@ func set_balls(type: GameBall.Type, value: int) -> void:
 
 ## Change the quantity of a ball type
 func mutate_balls(type: GameBall.Type, delta: int) -> void:
-	if _balls[type] >= 0:
+	if _balls.get(type, 0) >= 0:
 		_balls[type] = _balls.get(type, 0) + delta
 		on_balls_changed.emit(type, _balls[type])