title: Firebase modular (v9) incompatible with Expo
body: <p>I'm using Expo v42.0.1 and trying to install Firebase v9.0.2 and am unable to do so.</p>
  <h2>Issue</h2>
  <p>From running <code>expo install firebase</code>, firebase version 8.2.3 is installed. When changing the <code>package.json</code> to use firebase version 9.0.2, I get an error when running the app:</p>
  <blockquote>
  <p>&quot;firebase&quot; is added as a dependency in your project's package.json but it doesn't seem to be installed. Please run &quot;yarn&quot; or &quot;npm install&quot; to fix this issue.</p>
  </blockquote>
  <h2>What I've tried</h2>
  <ol>
  <li>Running <code>yarn / npm install</code></li>
  <li>Running <code>expo install firebase@9.0.2</code> (which ends up just downloading 8.2.3)</li>
  </ol>
  <p>Has anyone seen this before or know why it is happening? I believe it is because Expo v42 is not yet compatible with the <a href="https://firebase.google.com/docs/web/modular-upgrade" rel="nofollow noreferrer">modular version of firebase (v9)</a>.</p>