arp"><a href="../reference/reply.html"><span class="ci">Reply</span></a></code> value to <code
      class="fsharp"><a href="../reference/reply.html"><span class="ci">Reply</span></a><span class="cp">(</span><a
      href="../reference/primitives.html#members.Error"><span class="ci">Error</span></a><span class="cp">,</span> <span class="cnu">null</span><span
      class="cp">)</span></code>.
     </p>
    </div>
    <div class="para _5">
     <p>
      The error messages returned in the <code class="fsharp"