title: Apollo Server : throwing an error inside context always returns an http 400 error on the client
body: <p>So, i got an apollo server running and an apollo-client in my iOS app.</p>
  <p>I'm trying to implement an authentication process. And following <a href="https://www.apollographql.com/docs/apollo-server/security/authentication/" rel="nofollow noreferrer">apollo's documentation</a> about authorization and authentication, i ended up trying the code they provided :</p>
  <pre class="lang-js prettyprint-override"><code>
  context: ({ req }) =&gt; {
      throw new AuthenticationError('you must be logged in');
  },
  </code></pre>
  <p>But, while testing the code, i discovered that throwing an error wether it is a javascript one, or an apollo error, it always sends back an http 400 error :</p>
  <pre><code>Error: Response not successful: Received status code 400
      at new ApolloError (errors.cjs.js:31)
      at core.cjs.js:1493
      at both (utilities.cjs.js:963)
      at utilities.cjs.js:956
      at tryCallTwo (core.js:45)
      at doResolve (core.js:200)
      at new Promise (core.js:66)
      at Object.then (utilities.cjs.js:956)
      at Object.error (utilities.cjs.js:964)
      at notifySubscription (Observable.js:140)
  </code></pre>
  <p>The authentication error is not sent back. Even when i throw a custom error, with custom status code and everything it always returns the same error.</p>
  <p>Am i doing something wrong ? Or is this an issue ?</p>