错误:实例化模板实例时出错

req 太短了。以下是代码:

import std.stdio;
import vibe.d;

Database mydatabase;
void main()
{
    // ...
    router.get("*", &myStuff); // all other request
    listenHTTP(settings, router);

    runApplication();

}

@errorDisplay!showPageNotFound
void myStuff(HTTPServerRequest req, HTTPServerResponse res) // I need this to handle any accessed URLs
{
    if(req.path.length > 10) 
    {
    // ...
    }

    else
    {
        throw new Exception("Nothing do not found");
    }
}

void showPageNotFound(string _error = null)
{
    render!("error.dt", _error);
}

source\app.d(80,2): Error: template instance app.showPageNotFound.render!("error.dt", _error).render!("app", "app.showPageNotFound") error instantiating

如果我正在做:

void showPageNotFound(string _error = null)
{
    res.render!("error.dt", _error);
}

Error: undefined identifier 'res'