Add supply auto-purchase and preserve save recovery state

scripts/world/path_service.gd

@@ -1306,6 +1306,12 @@ func find_nearest_walkable_recovery(
 
 
 func create_snapshot() -> Dictionary:
+	# A nested sorted-name read can otherwise abort to an empty typed array
+	# while this outer capture still returns a seemingly valid Dictionary.
+	for transit_actor_id: Variant in _transit_actor_ids:
+		if typeof(transit_actor_id) not in [TYPE_STRING, TYPE_STRING_NAME]:
+			return {}
+
 	var connector_ids: Array = _connectors.keys()
 	connector_ids.sort_custom(Callable(self, "_string_name_less"))
 	var saved_connectors: Array = []