Fix drag race condition and stale pointer events

Mark items as dragging before updating inventory state to prevent
the spawner from destroying containers mid-drag. Move inventory
removal to drop time for lost items, and add guards to ignore
stale pointer events on inactive containers.

packages/sts-like-viewer/src/widgets/InventoryItemSpawner.ts

@@ -37,9 +37,10 @@ export interface InventoryItemSpawnerOptions {
  * Items currently being dragged are excluded from getData() to prevent
  * the spawner from respawning them while they're in flight.
  */
-export class InventoryItemSpawner
-  implements Spawner<InventoryItem<GameItemMeta>, Phaser.GameObjects.Container>
-{
+export class InventoryItemSpawner implements Spawner<
+  InventoryItem<GameItemMeta>,
+  Phaser.GameObjects.Container
+> {
   private scene: Phaser.Scene;
   private gameState: MutableSignal<RunState>;
   private parentContainer: Phaser.GameObjects.Container;
@@ -102,6 +103,7 @@ export class InventoryItemSpawner
     obj: Phaser.GameObjects.Container,
     _item: InventoryItem<GameItemMeta>,
   ): void {
+    obj.removeAllListeners();
     obj.destroy();
   }
 
@@ -248,6 +250,8 @@ export class InventoryItemSpawner
     container: Phaser.GameObjects.Container,
   ): void {
     container.on("pointerdown", (pointer: Phaser.Input.Pointer) => {
+      // Guard against stale events firing on destroyed containers
+      if (!container.scene || !container.active) return;
       if (this.isLocked()) return;
       if (this.isDragging()) return;
       if (pointer.button === 0) {