fix isDefaultItem check

src/lib/rpg/items.ts

@@ -368,7 +368,7 @@ export function getMaxStack(item: Item) {
 }
 
 export function isDefaultItem(item: Item): item is DefaultItem {
-  return (item as DefaultItem).behaviors !== undefined; // ough
+  return item.id < 0;
 }
 
 export function formatItem(item: Item | undefined, disableBold = false) {