You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: router_builder.rs
    path of file: ./repos/rspc/crates/core/src
    
    the code of the file until where you have to start completion: use std::{borrow::Cow, collections::BTreeMap, panic::Location};

use thiserror::Error;

use crate::{internal::ProcedureTodo, router::Router};

// TODO: Move into `procedure_store` module???
pub type ProcedureMap<TCtx> = BTreeMap<String, ProcedureTodo<TCtx>>;

/// TODO
#[derive(Debug, PartialEq, Eq)]
pub struct BuildError {
    pub(crate) cause: BuildErrorCause,
    #[cfg(debug_assertions)]
    pub(crate) name: Cow<'static, str>,
    #[cfg(debug_assertions)]
    pub(crate) loc: &'static Location<'stati
    
    pub fn unwrap(self) -> Router<TCtx> {
        match self {
            Self::Ok(router) => router,
            Self::Err(errors) => {
                #[cfg(debug_assertions)]
                {
                    eprintln!("Error building rspc router\n");

                    for error in &errors {
                        eprintln!("Error at '{}' with procedure '{}':", error.loc, error.name);
                        eprintln!("\t error: {}\n", error.cause);
                    }
                }

                #[cfg(not(debug_assertions))]
                {
                    eprintln!("Error building rspc router. Please use a debug build for proper error reporting.\n");
                }

                std::process::exit(1);
            }
        }
    }