Fix `deserialize_with` in module with Result alias
Fix `deserialize_with` in module with Result alias

Result<T, E> aliases usually provide one or both of `T` and `E`. This
would cause an error when using deserialize_with:

    error: wrong number of type arguments: expected 1, found 2

which unhelpfully just pointed to `#[derive(Deserialize)]`

erickt/serde,serde-rs/serde,oli-obk/rust-serde