RealityKit crashes when rendering SpriteKit scene with SKShapeNode in postProcess callback

I'm converting my game from SceneKit to RealityKit. It has a SpriteKit overlay that according to Explore advanced rendering with RealityKit 2 I can add with the code below.

The code runs fine if the SKScene only contains a SKSpriteNode (see the commented out line), but when I add a SKShapeNode with a fillColor instead, the app crashes with this error:

-[MTLDebugRenderCommandEncoder validateCommonDrawErrors:]:5970: failed assertion `Draw Errors Validation
MTLDepthStencilDescriptor uses frontFaceStencil but MTLRenderPassDescriptor has a nil stencilAttachment texture
MTLDepthStencilDescriptor uses backFaceStencil but MTLRenderPassDescriptor has a nil stencilAttachment texture
'

I don't know enough about low-level graphics and stencils yet to figure out a quick solution, so I would appreciate if anyone could share an easy fix or explanation of what's wrong. Thanks!

class ViewController: NSViewController {
    
    var device: MTLDevice!
    var renderer: SKRenderer!
    
    override func loadView() {
        let arView = ARView(frame: NSScreen.main!.frame)
        view = arView
        
        arView.renderCallbacks.prepareWithDevice = { [weak self] device in
            guard let self = self else { return }
            self.device = device
            renderer = SKRenderer(device: MTLCreateSystemDefaultDevice()!)
            let scene = SKScene()
            let shape = SKShapeNode(rectOf: CGSize(width: 10, height: 10))
            shape.fillColor = .red
            scene.addChild(shape)
//            scene.addChild(SKSpriteNode(color: .red, size: CGSize(width: 10, height: 10)))
            renderer.scene = scene
        }
        arView.renderCallbacks.postProcess = { [weak self] context in
            guard let self = self else { return }
            let encoder = context.commandBuffer.makeBlitCommandEncoder()
            encoder?.copy(from: context.sourceColorTexture, to: context.targetColorTexture)
            encoder?.endEncoding()
            renderer.update(atTime: context.time)
            let descriptor = MTLRenderPassDescriptor()
            descriptor.colorAttachments[0].loadAction = .load
            descriptor.colorAttachments[0].storeAction = .store
            descriptor.colorAttachments[0].texture = context.targetColorTexture
            renderer.render(withViewport: CGRect(x: 0, y: 0, width: context.targetColorTexture.width, height: context.targetColorTexture.height), commandBuffer: context.commandBuffer, renderPassDescriptor: descriptor)
        }
    }
    
}