Guard item.container against cycles (foundryvtt#15113)

src/module/item/physical/document.ts

@@ -33,7 +33,7 @@ abstract class PhysicalItemPF2e<TParent extends ActorPF2e | null = ActorPF2e | n
  * The cached container of this item, if in a container, or null
  * @ignore
  */
- private declare _container: ContainerPF2e<ActorPF2e> | null;
+ private declare _container?: ContainerPF2e<ActorPF2e> | null;
 
  /** Doubly-embedded adjustments, attachments, talismans etc. */
  declare subitems: Collection<PhysicalItemPF2e<TParent>>;
@@ -192,9 +192,8 @@ abstract class PhysicalItemPF2e<TParent extends ActorPF2e | null = ActorPF2e | n
 
  /** Get this item's container, returning null if it is not in a container */
  get container(): ContainerPF2e<ActorPF2e> | null {
- if (this.system.containerId === null) return (this._container = null);
- return (this._container ??=
- this.actor?.itemTypes.backpack.find((c) => c.id === this.system.containerId) ?? null);
+ this.updateContainerCache();
+ return this._container ?? null;
  }
 
  /** Returns the bulk of this item and all sub-containers */
@@ -250,7 +249,7 @@ abstract class PhysicalItemPF2e<TParent extends ActorPF2e | null = ActorPF2e | n
  }
 
  protected override _initialize(options?: Record<string, unknown>): void {
- this._container = null;
+ delete this._container;
  this.subitems ??= new Collection();
  super._initialize(options);
  }
@@ -293,9 +292,9 @@ abstract class PhysicalItemPF2e<TParent extends ActorPF2e | null = ActorPF2e | n
  equipped.inSlot = false;
  }
 
- // Set the _container cache property to null if it no longer matches this item's container ID
+ // Remove the _container cache property if it no longer matches this item's container ID
  if (this._container?.id !== this.system.containerId) {
- this._container = null;
+ delete this._container;
  }
 
  // Prepare doubly-embedded items if this is of an appropriate physical-item type
@@ -377,7 +376,8 @@ abstract class PhysicalItemPF2e<TParent extends ActorPF2e | null = ActorPF2e | n
 
  // Clear the container reference if it turns out to be stale
  if (this._container && !this.actor.items.has(this._container.id)) {
- this._container = this.system.containerId = null;
+ this.system.containerId = null;
+ delete this._container;
  }
 
  // Ensure that there is only one selected apex item, and all others are set to false
@@ -592,6 +592,23 @@ abstract class PhysicalItemPF2e<TParent extends ActorPF2e | null = ActorPF2e | n
  return game.i18n.format("PF2E.identification.UnidentifiedItem", { item: itemType });
  }
 
+ /** Updates this container's cache while also resolving cyclical references. Skips if already cached */
+ protected updateContainerCache(seen: string[] = []): void {
+ // If already cached or there is no container, return
+ if ("_container" in this) {
+ return;
+ }
+
+ const container = this.actor?.items.get(this.system.containerId ?? "") ?? null;
+ if (!container?.isOfType("backpack") || this.id === container.id || seen.includes(container.id)) {
+ this._container = null;
+ } else {
+ seen.push(this.id);
+ this._container = container;
+ container.updateContainerCache(seen);
+ }
+ }
+
  /** Include mystification-related rendering instructions for views that will display this data. */
  protected override traitChatData(dictionary: Record<string, string>): TraitChatData[] {
  const traitData = super.traitChatData(dictionary);