pub struct Element {
    lol: i32,
}

pub struct Container {
    element: Option<Element>,
}

pub struct Error {
    text: &'static str,
}

fn test<'a, I>(containers: I)
where
    I: Iterator<Item = Option<&'a Container>>,
{
    containers.map(|container| {
        let element = container
            .ok_or(Error {
                text: "container not found",
            })?
            .element
            .as_ref()
            .ok_or(Error { text: "no element" })?;

        Ok::<_, Error>(element)
    });
}