Move `onErrorResume` to individual `sendMessage` `Mono`

service/src/main/java/org/whispersystems/textsecuregcm/websocket/WebSocketConnection.java

@@ -360,7 +360,7 @@ public class WebSocketConnection implements MessageAvailabilityListener, Displac
         .limitRate(MESSAGE_PUBLISHER_LIMIT_RATE)
         .flatMapSequential(envelope ->
             Mono.fromFuture(() -> sendMessage(envelope)
-                .orTimeout(sendFuturesTimeoutMillis, TimeUnit.MILLISECONDS)))
+                    .orTimeout(sendFuturesTimeoutMillis, TimeUnit.MILLISECONDS))
                 .onErrorResume(
                     // let the first error pass through to terminate the subscription
                     e -> {
@@ -372,6 +372,7 @@ public class WebSocketConnection implements MessageAvailabilityListener, Displac
                     // otherwise just emit nothing
                     e -> Mono.empty()
                 )
+        )
         .subscribeOn(messageDeliveryScheduler)
         .subscribe(
             // no additional consumer of values - it is Flux<Void> by now