title: What does ` UNMET PEER DEPENDENCY <packageName> extraneous` mean?
body: <p>I understand that <code>UNMET PEER DEPENDENCY</code> means I need to <code>npm install</code> one of my <code>peerDependencies</code>. I <em>believe</em> that <code>extraneous</code> means the package exists but is not listed in <code>package.json</code> (presumably because it's installed globally?).</p>
  
  <p>What does it mean to have the two of them together?</p>
  
  <p>And why am I seeing this error even though I see these packages in <code>node_modules</code>, at the correct versions?</p>