title: how to fix broken npm after node update
body: <p>I updated node to 7.9.0 with homebrew. Now whenever I do anything with npm I get the following error:</p>
  
  <pre><code>$ node -v
  v7.9.0
  $ npm -v
  module.js:472
      throw err;
      ^
  
  Error: Cannot find module '../lib/utils/unsupported.js'
      at Function.Module._resolveFilename (module.js:470:15)
      at Function.Module._load (module.js:418:25)
      at Module.require (module.js:498:17)
      at require (internal/module.js:20:19)
      at /usr/local/lib/node_modules/npm/bin/npm-cli.js:19:21
      at Object.&lt;anonymous&gt; (/usr/local/lib/node_modules/npm/bin/npm-cli.js:79:3)
      at Module._compile (module.js:571:32)
      at Object.Module._extensions..js (module.js:580:10)
      at Module.load (module.js:488:32)
      at tryModuleLoad (module.js:447:12)
  </code></pre>
  
  <p>I have tried uninstalling and reinstalling node with no change.
  What can I try to recover from this?</p>