When navigating between links in the link traversal showcase, sometimes the scene fails to load, showing a black scene instead. I get the following error in the developer console:

Uncaught TypeError: Cannot read properties of undefined (reading 'parent')
    at WebGLRenderer.render (three.js:19705)
    at HTMLElement.value (a-scene.js:798)
    at bound (bind.js:12)
    at onAnimationFrame (three.js:18489)
    at XRSession.onAnimationFrame (three.js:9450)

I suspect that the scene is being rendered before the camera is attached. As a workaround, I added this condition to the a-scene render function:

// Don't render until we have a camera
if (this.camera !== undefined)
{
  renderer.render(this.object3D, this.camera);
}

This seemed to fix it, but I suspect there may be a better way of handling the underlying race condition. The scene can start rendering from two different places: after the 'loaded' event and after entering vr. When using the link navigation, it seems you can enter vr before the scene is loaded.

• A-Frame Version: 1.2.0
• Platform / Device: Oculus Quest 2 browser
• Reproducible Code Snippet or URL: examples/showcase/link-traversal/index.html