### 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
final TransportRequest request,
        final Task parentTask,
        final TransportRequestOptions options,
        final TransportResponseHandler<T> handler
    ) {
        request.setParentTask(localNode.getId(), parentTask.getId());
        sendRequest(connection, action, request, options, handler);
    }
    private <T extends TransportResponse> void sendRequestInternal(
        final Transport.Connection connection,
        final String action,
        final TransportRequest request,
        final TransportRequestOptions options,
        TransportResponseHandler<T> handler
    ) {
        if (connection == null) {
            throw new IllegalStateException("can't send request to a null connection");
        }
        DiscoveryNode node = connection.getNode();
        Supplier<ThreadContext.StoredContext> storedContextSupplier = threadPool.getThreadContext().newRestorableContext(true);
        ContextRestoreResponseHandler<T> responseHandler = new ContextRestoreResponseHandler<>(storedContextSupplier, handler);
        
        final long requestId = responseHandlers.add(new Transport.ResponseContext<>(responseHandler, connection, action));
        final TimeoutHandler timeoutHandler;
        if (options.timeout() != null) {
            timeoutHandler = new TimeoutHandler(requestId, connection.getNode(), action);
            responseHandler.setTimeoutHandler(timeoutHandler);
        } else {
            timeoutHandler = null;
        }