Function gauss_newton_log_checked 

pub fn gauss_newton_log_checked<S: ConformallyFlat<Point = Vec3, Vector = Vec3>>(
    space: &S,
    from: Vec3,
    to: Vec3,
    n_steps: u32,
    max_iters: u32,
) -> (Vec3, Option<LogError>)

gauss_newton_log with its failure reported instead of hidden; the vector is still the last finite iterate.