Godot: checking if the player character is on a particular tile (a ladder) in the tile map

player.gd

var on_ladder = false

func _physics_process(delta):

	var tilemap = get_parent().get_node("TileMap")
	if not tilemap == null:
		var map_pos = tilemap.world_to_map(position)
		var id = tilemap.get_cellv(map_pos)
		if id > -1:
			if tilemap.get_tileset().tile_get_name(id) == "ladder":
				on_ladder = true
			else:
				on_ladder = false
		else:
			on_ladder = false