These attributes are not guaranteed to exist. So they should either be used
conditionally, or with a fallback value. The fallback value for the opacity is
obvious, but for the radius it's more tricky. There is not a consistent fallback
value across Blender unfortunately. The one I used here is used in a couple of
places.
Pull Request: https://projects.blender.org/blender/blender/pulls/128847
2806d54320