Crash when express.Router() is used in different event loop

[marcbachmann]

In my application I'm using the express.Router() class which got introduced in express v4.
I get an error when I try to initialize a route in a second event loop:

/app/node_modules/newrelic/lib/instrumentation/shared/connect-express.js:135
          if (m.handle !== sentinel) {
               ^
TypeError: Cannot read property 'handle' of null
  at cb_filter (/app/node_modules/newrelic/lib/instrumentation/shared/connect-express.js:135:16)
  at Array.filter (native)
  at Function.cls_wrapMiddlewareStack [as route] (/app/node_modules/newrelic/lib/instrumentation/shared/connect-express.js:128:31)
  at Function.proto.(anonymous function) [as get] (/app/node_modules/express/lib/router/index.js:446:22)
  at [object Object].<anonymous> (/app/index.coffee:10:10)
  at [object Object]._onTimeout (/app/node_modules/newrelic/node_modules/continuation-local-storage/node_modules/async-listener/glue.js:177:31)
  at Timer.listOnTimeout [as ontimeout] (timers.js:110:15)

How to reproduce it

In this example I force a new event loop using nextTick. But in reality I have some routes and some middlewares. That's why a few routes are initialized in a second event loop without calling nextTick.

1. Create file: index.js

require('newrelic');
var express = require('express');
var router = express.Router();

router.get('/test', function(req, res, next) {
  console.log('test');
  next();
});

process.nextTick(function() {
  router.get('/test', function(req, res, next) {
    console.log('test');
    next();
  });
});

1. Execute: node index.js

---

I'm using express v4.4.3, newrelic v1.7.2

[groundwater]

Looks like this is the same as #154

I'm going to pull your repro case into there

[marcbachmann]

Oh, I didn't notice that the problem always occurs with two route[verb] actions.
I thought there's only a problem when there are two event loops.
Thanks for pointing to the other issue and picking this up.