Playground displays SKTileMapNode as red square

Here is my code:

/ 
import AppKit
import GameKit
import PlaygroundSupport
let frame = CGRect(x:0, y:0, width: 300, height: 300)
let view = SKView(frame: frame)
PlaygroundPage.current.liveView = view
class LakeScene : SKScene {
   
   
    override func didMove(to view: SKView) {
        super.didMove(to: view)
       
       
        guard let tileSet = SKTileSet(named: "Sample Grid Tile Set") else {
            fatalError("Tile Set not found")
        }
       
        let tileSize = CGSize(width: 128.0, height: 128.0)
        let tileMap = SKTileMapNode(tileSet: tileSet, columns: 1, rows: 1, tileSize: tileSize)
       
        guard let waterTileGroup = tileSet.tileGroups.first(where: {$0.name == "Water"})  else {
            fatalError("Tile Group not found")}
        tileMap.fill(with: waterTileGroup)
       
        addChild(tileMap)
       
       
    }
   
}
let scene = LakeScene()
view.presentScene(scene)
 

I am using the example Tile Set that you get when you make a SpriteKit Tile Set file. I make the file then drag it and the Assets.xcassets into my Playground's Resources folder.

Here is a screenshot:

http://imgur.com/a/K8ugJ