When there is no default color attribute yet, when creating a new color
attribute with the store named attribute node, set the default. Though
we generally try to avoid this more magical behavior, there's little
downside in this case, and it's probably what users expect.
Don't set the active attribute though, since that's UI data that generally
shouldn't be changed procedurally. It's okay if there's no active color
attribute.
Pull Request: https://projects.blender.org/blender/blender/pulls/117249
83b7b729a1