1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
use std::{error, fmt}; /// Error returned if the inner `Service` has not been set. #[derive(Debug)] pub struct None(()); pub(crate) type Error = Box<dyn error::Error + Send + Sync>; impl None { pub(crate) fn new() -> None { None(()) } } impl fmt::Display for None { fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result { write!(fmt, "None") } } impl error::Error for None {}