title: Cannot find module 'google-cloud/pubsub' when deploying app
body: <p>I'm currently working on a google cloud project that involves moving data from PubSub to Datastore. This is being run on a google cloud appengine instance that is running as a resident application. I started working on the datastore part first with no trouble, but when it came to supporting pubsub the app crashes when I try to include it. </p>
  
  <pre><code>//including datastore
  const Datastore = require('@google-cloud/datastore');
  const datastore = Datastore();
  //including pubsub
  const PubSub = require('@google-cloud/pubsub');
  const pubsub = new PubSub();
  </code></pre>
  
  <p>What I don't understand is how these two commands are practically identical and only the pubsub part crashes. The google-cloud documentation lays this out as the way to include pubsub into the project. I also tried loading the package locally through npm with no success. </p>
  
  <p>What can be done to alleviate this issue? Thanks in advance.</p>