Fix concurrency errors

src/main/java/it/tdlight/common/InternalClient.java

@@ -76,6 +76,7 @@ public class InternalClient implements ClientEventsHandler, TelegramClient {
 			handleResponse(eventId, new Error(500, "Instance closed"), handler);
 		});
 		handlers.clear();
+		logger.info("Client closed {}", clientId);
 	}
 
 	/**

src/main/java/it/tdlight/common/InternalClientManager.java

@@ -51,11 +51,11 @@ public class InternalClientManager implements AutoCloseable {
 	}
 
 	public void registerClient(int clientId, ClientEventsHandler internalClient) {
-		responseReceiver.registerClient(clientId);
 		boolean replaced = registeredClientEventHandlers.put(clientId, internalClient) != null;
 		if (replaced) {
 			throw new IllegalStateException("Client " + clientId + " already registered");
 		}
+		responseReceiver.registerClient(clientId);
 	}
 
 	public String getImplementationName() {

src/main/java/it/tdlight/common/InternalReactiveClient.java

@@ -134,6 +134,7 @@ public class InternalReactiveClient implements ClientEventsHandler, ReactiveTele
 					if (isClosed.get()) {
 						if (alreadyCompleted.compareAndSet(false, true)) {
 							subscriber.onComplete();
+							logger.info("Client closed {}", clientId);
 						}
 					}
 				}

src/main/java/it/tdlight/common/ResponseReceiver.java

@@ -8,7 +8,7 @@ import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
-import java.util.concurrent.ConcurrentSkipListSet;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CountDownLatch;
 import java.util.stream.Collectors;
 
@@ -32,7 +32,7 @@ public class ResponseReceiver extends Thread implements AutoCloseable {
 	private final TdApi.Object[] events = new TdApi.Object[MAX_EVENTS];
 
 	private final CountDownLatch closeWait = new CountDownLatch(1);
-	private final Set<Integer> registeredClients = new ConcurrentSkipListSet<>();
+	private final Set<Integer> registeredClients = new ConcurrentHashMap<Integer, java.lang.Object>().keySet(new java.lang.Object());
 	private volatile boolean closeRequested = false;