Crash when preloading SKTextureAtlas in Swift 6

I have the following code:

import UIKit import SpriteKit class ViewController: UIViewController { let textureAtlas: SKTextureAtlas required init?(coder: NSCoder) { textureAtlas = SKTextureAtlas(dictionary: ["Foo": UIImage(named: "foo.png")!]) super.init(coder: coder) textureAtlas.preload { } } } 

You can add a random foo.png file to your project. Then running it with Swift 6 mode will crash:

Thread 4 Queue : com.apple.spritekit.preloadQueue (concurrent) #0 0x00000001099476f5 in _dispatch_assert_queue_fail () #1 0x000000010994768f in dispatch_assert_queue () #2 0x00007ffc10f5f251 in swift_task_isCurrentExecutorImpl () #3 0x0000000109e05f39 in closure #1 in ViewController.init(coder:) () #4 0x0000000109e05fa8 in thunk for @escaping @callee_guaranteed () -> () () #5 0x0000000109944b3d in _dispatch_call_block_and_release () #6 0x0000000109945ec6 in _dispatch_client_callout () #7 0x00000001099490f3 in _dispatch_continuation_pop () #8 0x0000000109947f20 in _dispatch_async_redirect_invoke () #9 0x0000000109959d2c in _dispatch_root_queue_drain () #10 0x000000010995a8ef in _dispatch_worker_thread2 () #11 0x00000001093c4b43 in _pthread_wqthread () #12 0x00000001093c3acf in start_wqthread () Enqueued from com.apple.spritekit.preloadQueue (Thread 4) Queue : com.apple.spritekit.preloadQueue (serial) #0 0x0000000109946bf1 in _dispatch_group_wake () #1 0x0000000109949239 in _dispatch_continuation_pop () #2 0x0000000109947f20 in _dispatch_async_redirect_invoke () #3 0x0000000109959d2c in _dispatch_root_queue_drain () #4 0x000000010995a8ef in _dispatch_worker_thread2 () #5 0x00000001093c4b43 in _pthread_wqthread () #6 0x00000001093c3acf in start_wqthread () 

I have tried:

• Use Swift 5, with strict concurrency checking. No crash, no warning.
• Keep Swift 6, but remove the preload call. No crash. However, I need this preload for performance reason during the game.

I am not sure why it crashes here. The stack trace is assembly code.