尝试索引全局“应用程序”（nil值）错误

我试图按照Lua类的语言学习语言，并在尝试运行程序以查看标题时出现错误的第17行

lua: [string "<eval>"]:1: attempt to index global 'application' (a nil value)
stack traceback:
        [string "<eval>"]:1: in main chunk

这是我编写的所有代码以及课程的链接

application:setOrientation(Application.LANDSCAPE_LEFT

application:setScaleMode("letterbox")

BLACK @ 0x1A1A1A 
application:setBackgroundColor(BLACK)

local fg = Bitmap.new(Texture.new("images/foreground.png", true))
fg:setX(1201)
stage:addChild(fg)

YELLOW @ 0xDAD45E 
local title = TextField.new(nil, "The Long Dark") 
title:setTextColor(YELLOW) 
title:setPosition(1320, 100)
stage:addChild(title)

https://programmingbymoonlight.com/roguelike-part-1-lua-and-gideros-an-introduction/