Change how map loading works

nodes/player_controller.gd

@@ -72,9 +72,8 @@ func _select_unit(unit: Unit) -> void:
 
 func _get_unit_at(world_pos: Vector2) -> Unit:
 	var snapped := dl_map.snap_to_grid(world_pos)
-	for child in get_parent().get_children():
-		if child is Unit:
-			var unit_snapped := dl_map.snap_to_grid(child.global_position)
-			if unit_snapped == snapped:
-				return child
+	for unit: Unit in get_tree().get_nodes_in_group("units"):
+		var unit_snapped := dl_map.snap_to_grid(unit.global_position)
+		if unit_snapped == snapped:
+			return unit
 	return null