@PiggyCat FYI the suggestion from earlier will fix the exception, but there might still be issues.
First off, I just released an update to fix some bugs. The shader I use to perform raycasts did not render non-person atoms correctly, which meant they wouldn't occlude persons. Also, I used the wrong layer mask as a default, and I'm seeing you're trying to raycast on layer 29, too. But actually all atoms are rendered on the default layer (so layer mask = 1). I just got lucky because I forgot to bit shift, so I did not notice anything wrong

The default of the Raycast function is now set correctly, and you shouldn't even need to pass a layer mask yourself.
Secondly, I forgot to mention an important detail in the resource description:
So you'll need to do something like this:
C#:
private void YourFunction()
{
StartCoroutine(YourRaycast());
}
private IEnumerator YourRaycast()
{
yield return new WaitForEndOfFrame();
[...]
if (gpuRaycast.Api?.Raycast(...) == true) { [...] }
}