Redirect http GET request on first application run/startup (for initialization)

I'd like to redirect a request to another module if the application is being run for the first time (nancy).

// bootstrapper -> RequestStartup
pipelines.BeforeRequest.AddItemToEndOfPipeline(context =>
    if(!_configuration.FirstRun)
        return null;

    return context.Request.Path != "/app/firstrun" ?
        context.GetRedirect("/app/firstrun") : null;
});

The pipeline get's intercepted and the redirection happens - however I somehow loose all information about the request and thus, the AppModule never get's called. It also tries to locate a view called "DefaultStatusCodeHandlerResult" somehow (?) which obviously doesn't exist.

// app module
public class AppModule : NancyModule {
    public AppModule(ServerConfiguration configuration) {
        Get["firstrun"] = _ => {
            if(!configuration.FirstRun)
                return Response.AsRedirect("/home/");
            return View["FirstRun"];  
        };
    }
}

Am I doing something wrong? Or is there a better place to configure this behavior instead of the before request pipeline?