title: webpack --watch isn't compiling changed files
body: <p>I tried running <code>webpack --watch</code> and after editing my JS files, it doesn't trigger an auto-recompilation. </p>
  
  <p>I've tried reinstalling <code>webpack</code> using <code>npm uninstall</code> but it's still not working.</p>
  
  <p>Any ideas?</p>