discord-ws: Fix heartbeat timing

Wait til sending complets and then start the sleep.

discord-ws/src/main/java/de/hhhammer/dchat/discord/ws/connection/listener/DiscordListener.java

@@ -15,6 +15,7 @@ import java.util.Optional;
 import java.util.Random;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.CompletionStage;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -89,11 +90,15 @@ public final class DiscordListener implements WebSocket.Listener {
             case 7 -> {
                 logger.info("Reconnect request");
                 this.closeEventQueue.add(new CloseEvent.ResumableCloseEvent(this.resumeGatewayUrl.get(), this.sessionId.get(), lastSeq.get()));
+                webSocket.request(1);
+                return webSocket.sendClose(WebSocket.NORMAL_CLOSURE, "reconnect").thenAccept(WebSocket::abort);
             }
             // invalid session
             case 9 -> {
                 logger.info("Invalid session");
                 this.closeEventQueue.add(new CloseEvent.UnresumableCloseEvent()); // it's technically possible to resume but unlikely -> https://discord.com/developers/docs/events/gateway#resuming
+                webSocket.request(1);
+                return webSocket.sendClose(WebSocket.NORMAL_CLOSURE, "invalid session").thenAccept(WebSocket::abort);
             }
             // hello event
             case 10 -> init(webSocket, event.data());
@@ -151,12 +156,14 @@ public final class DiscordListener implements WebSocket.Listener {
                     final String stringSeq = intSeq != 0 ? String.valueOf(intSeq) : "null";
                     // Send heartbeat
                     logger.debug("Sending heartbeat: {}", stringSeq);
-                    webSocket.sendText("{\"op\": 1, \"d\": %s}".formatted(stringSeq), true);
+                    webSocket.sendText("{\"op\": 1, \"d\": %s}".formatted(stringSeq), true).get();
                     receivedAck.set(false);
                     TimeUnit.MILLISECONDS.sleep(heartbeatInterval);
                 }
             } catch (InterruptedException e) {
                 logger.error("Heartbeat interrupted", e);
+            } catch (ExecutionException e) {
+                logger.error("Heartbeat send failed", e);
             }
             logger.info("Stopping heartbeat");
         });