### 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
}
        @Override
        public void incRef() {}
        @Override
        public boolean tryIncRef() {
            return true;
        }
        @Override
        public boolean decRef() {
            return false;
        }
        @Override
        public boolean hasReferences() {
            return true;
        }
        @Override
        public void onRemoved() {
            assert false : "should not remove the local node connection";
        }
        @Override
        public String toString() {
            return "local node connection";
        }
    };
    public TransportService(
        Settings settings,
        Transport transport,
        ThreadPool threadPool,
        TransportInterceptor transportInterceptor,
        Function<BoundTransportAddress, DiscoveryNode> localNodeFactory,