for #25816 skip dependency check for read nodes with empty filenames

If read nodes in the current script have their file knob set to `""` by a script, this will return `None` when reading the file knob value back which causes an error when trying to replace the path separator. This fix checks to make sure we have an actual (non-empty) file name before continuing on to try and match it with a template. If the `file_name` is an empty string or `None`, we skip the check and move on error free.