That means it can not find a Sacred Shield status to assign to corner-top-right-color. It does not break anything, so you can ignore it. On the other hand it means I need to find out how it happened so I can handle it better in the future.
As far as I know it happens when you delete an indicator on character x and log onto another char where nothing was changed before and the defaults try to use things that have been deleted - roughly said. To be honest I switched over to Grid again because it is more mature and I am used to it - but Grid2 will be a good substituion when it is mature I am sure, coming along nicely. :)