fix: empty page on @Render() responds with 404

[jaimeadf]

Description

When the page specified in the @Render() decorator returns an empty string, the server responds with the status code 404 (Not Found).

Minimal code-snippet showcasing the problem

import { Controller, Get, Render } from 'routing-controllers';

@Controller()
export class MyController {
    @Get()
	@Render('index.pug') // index.pug must be empty
	index() {
		
	}
}

Expected behavior

The server should send an empty body and respond with 200 (OK).

Actual behavior

The server sends the error page and responds with 404 (Not Found).