update

scenes/world/portal_spawner.gd

@@ -41,4 +41,8 @@ func _spawn_portal() -> void:
   portals.append(portal)
 
 func _cleanup_dead() -> void:
-  portals = portals.filter(func(p: Node) -> bool: return is_instance_valid(p))
+  var valid: Array[Node] = []
+  for p in portals:
+    if is_instance_valid(p):
+      valid.append(p)
+  portals = valid