installing yo and seeing it be forgotten

gistfile1.txt

$ npm list yo
/Users/walther
└── (empty)

npm ERR! code 1
$ npm install -g yo
npm WARN deprecated npmconf@2.1.2: this package has been reintegrated into npm and is now out of date with respect to npm
/Users/walther/.node/bin/yo -> /Users/walther/.node/lib/node_modules/yo/lib/cli.js
/Users/walther/.node/bin/yo-complete -> /Users/walther/.node/lib/node_modules/yo/lib/completion/index.js

> yo@1.8.5 postinstall /Users/walther/.node/lib/node_modules/yo
> yodoctor


Yeoman Doctor
Running sanity checks on your system

✔ Global configuration file is valid
✔ Node.js version
✔ No .bowerrc file in home directory
✔ No .yo-rc.json file in home directory
✔ npm version
✔ NODE_PATH matches the npm root

Everything looks all right!
/Users/walther/.node/lib
└── yo@1.8.5 

$ npm list yo
/Users/walther
└── (empty)

npm ERR! code 1
$ yo
? 'Allo Walther! What would you like to do? Get me out of here!

     _-----_     ╭───────────────────────╮
    |       |    │      Bye from us!     │
    |--(o)--|    │       Chat soon.      │
   `---------´   │      Yeoman team      │
    ( _´U`_ )    │    http://yeoman.io   │
    /___A___\   /╰───────────────────────╯
     |  ~  |     
   __'.___.'__   
 ´   `  |° ´ Y ` 

$ npm -v
3.10.3
$ node -v
v6.5.0
$ npm config get registry
https://registry.npmjs.org/
$ uname -a
Darwin Store-Bukkebruse.local 15.6.0 Darwin Kernel Version 15.6.0: Mon Aug 29 20:21:34 PDT 2016; root:xnu-3248.60.11~1/RELEASE_X86_64 x86_64
$ npm list yo
/Users/walther
└── (empty)

npm ERR! code 1
$ which yo
$