title: Can't get the error to hit a catch block while running query on datastore
body: <p>I'm passing an undefined parameter to the below method causing datastore client to:</p>
  
  <p><em>throw new Error('Unsupported field value, ' + value + ', was provided.');
  Error: Unsupported field value, undefined, was provided.</em></p>
  
  <p>I'm expecting the inner catch statement to be hit with the error but neither that one nor the outer try catch is getting hit. The error handling middle isn't catching this error either and it's crashing my expressjs app.</p>
  
  <pre><code>getUserByEmail(email) {
      try {
          return datastore
              .createQuery("user")
              .filter("email", "=", email)
              .limit(1)
              .run()
              .then(results =&gt; {
                  var entities = results[0][0];
                  return entities;
              })
              .catch((error) =&gt; {
                  console.error(error);
                  return null;
              });
      }
      catch (error) {
          console.error(error);
          return null;
      }
  }
  </code></pre>
  
  <p>What am I missing here?</p>