Function read_nonsource_file_entries_with_reader 

fn read_nonsource_file_entries_with_reader<E, F>(
    config: &AtlasMapConfig,
    read_text: &mut F,
) -> Result<NonsourceEntries, E>
where
    E: From<AtlasMapError>,
    F: FnMut(&Path) -> Result<String, E>,

Read non-source purpose rows through a caller-owned bounded text reader.