Error transformation does not work when serving static files

[WillCodeCo]

I want to make a 404 error pretty. Problem is that I cannot seem to hook the error properly. This code demonstrates the problem:

// Generated by CoffeeScript 1.6.3
(function() {
  var Hapi, app_root_dir, get, is_production, options, path, routes, server, server_root_dir;

  Hapi = require('hapi');

  path = require('path');

  is_production = function() {
    return process.env.NODE_ENV === 'production';
  };

  server_root_dir = path.resolve('./');

  app_root_dir = path.join(server_root_dir, 'app');

  options = {
    cors: {
      origin: ['*']
    },
    debug: is_production() ? false : {
      request: ['error', 'uncaught']
    }
  };

  server = new Hapi.Server('localhost', (is_production() ? 80 : 8080), options);

  server.ext('onPreResponse', function(request, next) {
    var response;
    response = request._response;
    if (!response.isBoom) {
      return next();
    }
    return next({
      a_pretty_json: 'well not really'
    });
  });

  get = function(path, config) {
    return {
      path: path,
      method: 'GET',
      config: config
    };
  };

  routes = [
    get('/', {
      handler: function(request) {
        return request.reply({
          hello: 'world'
        });
      }
    }), get('/{path*}', {
      handler: {
        directory: {
          path: app_root_dir,
          listing: false,
          index: true
        }
      }
    })
  ];

  server.route(routes);

  server.start();

}).call(this);