Fix warning that filenames might not be set
I see this warning in VSCode not sure why CI does not flag it.
It's saying it cannot guarantee that filenames will be assigned to
anything. Even though resumably in our usage it is.
@@ -390,6 +390,7 @@ class AddLayersMixin:
# glean layer names from filename. These will be used as *fallback*
# names, if the plugin does not return a name kwarg in their meta dict.
+ filenames = []
if isinstance(path_or_paths, str):
filenames = itertools.repeat(path_or_paths)
elif is_sequence(path_or_paths):
