module resolution can fail with trailing slash

[targos]

• Version: 6.0.0-rc.2 / master
• Platform: Linux 4.5.0-302.fc24.x86_64 deps: update openssl to 1.0.1j #1 SMP Wed Mar 30 15:41:34 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
• Subsystem: module

I discovered this bug while trying to run pm2 with v6.0.0-rc.2.

To repro, create the following directory structure:

test
test/test.js
test/node_modules/a/package.json

test/test.js:

require('a/');

test/node_modules/a/package.json:

{
  "main": "doesnotexist"
}

Then execute test/test.js.

Result with v5.10.1:

module.js:341
    throw err;
    ^

Error: Cannot find module 'a/'
    at Function.Module._resolveFilename (module.js:339:15)
    at Function.Module._load (module.js:290:25)
    at Module.require (module.js:367:17)
    at require (internal/module.js:16:19)
    at Object.<anonymous> (/home/mzasso/test/test.js:1:63)

Result with v6.0.0-rc.2 / master:

module.js:128
  for (var i = 0; i < exts.length; i++) {
                          ^

TypeError: Cannot read property 'length' of undefined
    at tryExtensions (module.js:128:27)
    at tryPackage (module.js:107:10)
    at Function.Module._findPath (module.js:182:18)
    at Function.Module._resolveFilename (module.js:434:25)
    at Function.Module._load (module.js:384:25)
    at Module.require (module.js:464:17)
    at require (internal/module.js:16:19)
    at Object.<anonymous> (/home/mzasso/test/test.js:1:63)

I'm working on a fix right now.