### Description

The `sendRequest` method is asynchronous and notifies a 
`TransportResponseHandler` when it completes the excecution
(successfully or unsuccessfully). 

When opening the connection we only catch `NodeNotConnectedException`
( https://github.com/elastic/elasticsearch/blob/main/server/src/main/java/org/elasticsearch/transport/TransportService.java#L719 ) which is currently fine as no implementations
throw other type of exception however, it'd be best to catch `Exception` here
so the `handler` gets notified of potential exceptions (as opposed to the caller
having to `try/catch` the call to `sendRequest`)
server/src/main/java/org/elasticsearch/transport/TransportService.java
import org.elasticsearch.core.AbstractRefCounted;
import org.elasticsearch.core.IOUtils;
import org.elasticsearch.core.Nullable;
import org.elasticsearch.core.Releasable;
import org.elasticsearch.core.TimeValue;
import org.elasticsearch.node.NodeClosedException;
import org.elasticsearch.node.ReportingService;
import org.elasticsearch.tasks.Task;
import org.elasticsearch.tasks.TaskManager;
import org.elasticsearch.threadpool.Scheduler;
import org.elasticsearch.threadpool.ThreadPool;
import org.elasticsearch.tracing.Tracer;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.net.UnknownHostException;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.function.Function;
import java.util.function.Predicate;
import java.util.function.Supplier;
import static org.elasticsearch.core.Strings.format;
public class TransportService extends AbstractLifecycleComponent