### 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/cluster/coordination/CoordinationDiagnosticsService.java
currentMaster = new DiscoveryNode(in);
            } else {
                currentMaster = null;
            }
            return currentMaster;
        }
        private static List<DiscoveryNode> readRecentMasters(StreamInput in) throws IOException {
            boolean hasRecentMasters = in.readBoolean();
            List<DiscoveryNode> recentMasters;
            if (hasRecentMasters) {
                recentMasters = in.readImmutableList(DiscoveryNode::new);
            } else {
                recentMasters = null;
            }
            return recentMasters;
        }
        private static Map<String, String> readClusterFormationStates(StreamInput in) throws IOException {
            if (in.readBoolean()) {
                return in.readMap(StreamInput::readString, StreamInput::readString);
            } else {
                return Map.of();
            }
        }
        private static String getStackTrace(Exception e) {
            if (e == null) {
                return null;
            }
            StringWriter stringWriter = new StringWriter();
            e.printStackTrace(new PrintWriter(stringWriter));
            return stringWriter.toString();