Help please i keep on getting an error Thread message. Thanks

Heres the code hope you can help me thanks.
It comes up as Thread 1: EXC_BAD_INSTRUCTION (code=EXC_l386_INVOP,subcode = EXC_1386_INVOP,subcode=0*0)
The line that it is on is: let overlayScene = SKScene(fileNamed: fileName)!

import SpriteKit
import CoreMotion

class GameScene: SKScene {

let manager = CMMotionManager()

//MARK: - Properties
var bgNode = SKNode()
var fgNode = SKNode()
var background: SKNode!
var backHeight: CGFloat = 0.0
var player: SKSpriteNode!
var platform5Across: SKSpriteNode!
var coinArrow: SKSpriteNode!
var lastItemPosition = CGPointZero
var lastItemHeight: CGFloat = 0.0
var levelY: CGFloat = 0.0

override func didMoveToView(view: SKView) {
    setupNodes()
    
    manager.startAccelerometerUpdates()
    manager.accelerometerUpdateInterval = 0.1
    manager.startAccelerometerUpdatesToQueue(NSOperationQueue.mainQueue()){
        (data, error) in
        
        self.physicsWorld.gravity = CGVectorMake(CGFloat((data?.acceleration.x)!) * 10, CGFloat((data?.acceleration.y)!) * 10)   }
    
}

func setupNodes(){
    let worldNode = childNodeWithName("World")!
    bgNode = worldNode.childNodeWithName("Background")!
    background = bgNode.childNodeWithName("Overlay")!.copy()
    as! SKNode
    backHeight = background.calculateAccumulatedFrame().height
    fgNode = worldNode.childNodeWithName("Foreground")!
    fgNode.childNodeWithName("Bomb")?.runAction(SKAction.hide())
    platform5Across = loadOverlayNode("Platform5Across")
    coinArrow = loadOverlayNode("CoinArrow")        }

// MARK: Platform/Coin overlay nodes.
func loadOverlayNode(fileName: String) -> SKSpriteNode {
    l**et overlayScene = SKScene(fileNamed: fileName)!**
    let contentTemplateNode =
    overlayScene.childNodeWithName("Overlay")
    return contentTemplateNode as! SKSpriteNode        }

func createOverlayNode(nodeType: SKSpriteNode, flipX: Bool) {
        let platform = nodeType.copy() as! SKSpriteNode
        lastItemPosition.y = lastItemPosition.y +
        (lastItemHeight + (platform.size.height  /  2.0))
        lastItemHeight = platform.size.height / 2.0
        platform.position = lastItemPosition
        if flipX == true {
        
        platform.xScale = -1.0
        
        }
        fgNode.addChild(platform)
    }
    func createBackgroundNode() {
        let backNode = background.copy() as! SKNode
        backNode.position = CGPoint(x: 0.0, y: levelY)
        bgNode.addChild(backNode)
        levelY += backHeight
       
    
    func setupLevel() {
        //Place initial platform
        let initialPlatform = platform5Across.copy() as! SKSpriteNode
        var itemPosition = player.position
        itemPosition.y = player.position.y -
        ((player.size.height * 0.5) +
        (initialPlatform.size.height * 0.320))
        initialPlatform.position = itemPosition
        fgNode.addChild(initialPlatform)
        lastItemPosition = itemPosition
        lastItemHeight = initialPlatform.size.height / 2.0
        
        
    }
}



}

What was the value of fileName when the crash happened? Have you checked that filename against the .sks files in your app bundle?