title: Firestore Transactions do not work
body: <p>I found <a href="https://github.com/flutter/flutter/issues/14655" rel="nofollow noreferrer">some issue thread</a> with people also not being able to complete transactions, but it does not even provide <em>solutions</em>.</p>
  
  <h2>Problem</h2>
  
  <p>Suddenly, my <a href="https://github.com/flutter/flutter/issues/18870" rel="nofollow noreferrer">transactions crashes</a> when using <code>transaction.get</code>.</p>
  
  <pre><code>runTransaction(
    (Transaction transaction) async {
      await transaction.get(documentReference); // "Timed out waiting for Task"
    }
  </code></pre>
  
  <p>The <em><code>PlatformException</code></em> does also not really help me because it crashes in <code>platform_channel</code>...</p>
  
  <pre><code>E/flutter (16297): [ERROR:topaz/lib/tonic/logging/dart_error.cc(16)] Unhandled exception:
  E/flutter (16297): PlatformException(Error performing transaction, Timed out waiting for Task, null)
  E/flutter (16297): #0      StandardMethodCodec.decodeEnvelope (package:flutter/src/services/message_codecs.dart:547:7)
  E/flutter (16297): #1      MethodChannel.invokeMethod (package:flutter/src/services/platform_channel.dart:279:18)
  E/flutter (16297): &lt;asynchronous suspension&gt;
  E/flutter (16297): #2      Firestore.runTransaction (file:///G:/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.7.3/lib/src/firestore.dart:115:10)
  // here comes another &lt;asynchronous suspension&gt; followed by my code
  </code></pre>
  
  <p>This comes from <em>Android</em>.</p>