Function files_in_dirs_by_extension 

fn files_in_dirs_by_extension(
    dirs: &[PathBuf],
    extension: &str,
) -> Result<Vec<PathBuf>, Error>

Collects all regular files in a list of directories and filters them by extension.

Skips non-existent paths in dirs. Only considers regular files, that have a matching extension.

Errors

Returns an error if

• the entries in a directory in one of the paths in dirs cannot be read
• one of the entries in a directory cannot be read