restructure casting to avoid crash

llarp/dnsd.cpp

@@ -268,9 +268,10 @@ handle_dnsc_result(dnsc_answer_request *client_request)
   }
   else
   {
-    writesend_dnss_response(
+    struct sockaddr *useHostRes = nullptr;
-        client_request->found ? client_request->result : nullptr,
+    if (client_request->found)
-        server_request->from, server_request);
+      useHostRes = client_request->result;
+    writesend_dnss_response(useHostRes, server_request->from, server_request);
   }
   llarp_host_resolved(client_request);
 }