title: Custom handling Future failures in Akka Streams Flow
body: <p>I try to connect multiple Flows in Akka Streams and handle their errors in different ways depending on the Flow. It can be accomplished using sth like that:</p>
  
  <pre><code>Flow[String, Either[ProcessingError, String], NotUsed]
  </code></pre>
  
  <p>And then divert response to error handler based on Either value.</p>
  
  <p>My problem is, that some Flows return Future[String] instead of String and I don't know how to evaluate it to be able to catch error after each Flow and handle it in custom way. </p>