Issue Template:

Describe issue including what OS you are using

macOS Sierra 10.12.6. #498 seems to have broken being able to list/switch between versions.

Describe what version of N you have

2.1.10

Describe how you installed N

N is installed via Homebrew.

Steps to reproduce issue 1.2.3

1. n

Describe the results you received

sort: stray character in field spec: invalid field specification '2,2V' 

  Error: no installed version

  Usage: n [options/env] [COMMAND] [args]

...

Describe the results you expected

A list of installed versions of node should be displayed, with the ability to switch. 8.11.1 is currently installed.

What version of npm you are using

6.0.0