17842d4d40
Due to a recent change the name of a layer is passed using a string ref
but the check if it is filled was done by checking if the first char
was zero. This fails as string ref first does the bound checks.
This is fixed by using `!is_empty()`. There might be more places, but this
one fired when loading production files.
Issue introduced by a39e8a4ab9
Pull Request: https://projects.blender.org/blender/blender/pulls/118605