title: Find conflicting versions between package-lock.json and yarn.lock when both exists
body: <p>I have some cases where in one project I have both <code>package-lock.json</code> and <code>yarn.lock</code> files (this is done unintentionally, but it's not relevant at the moment) - In order to remove one of them (personally I prefer leaving the <code>yarn.lock</code> file) - I first need to know what are the differences between them, for that I can see two different solution :</p>
  
  <ol>
  <li>Finding difference in version between the two files (packages that are listed in both in different version / packages that are listed in only one of lock files)</li>
  <li>Delete both lock files, and generate a new one from the packages that are actually installed in my <code>node_modules</code> folder</li>
  </ol>
  
  <p>I found no command to do both (I'd expect yarn to provide that, since yarn is "npm compatible" and not the other way around)</p>
  
  <p>I found <code>yarn generate-lock-entry</code> whose name suggest that it should be relevant for my 2nd option - but it has nothing to do with that</p>
  
  <p>Any Idea?
  Thanks!</p>