Address other cases in which a replica read should be used based on the ResponseStatus that is returned by the SDK.

The replica example  on https://developer.couchbase.com/documentation/server/4.6/sdk/nodejs/failure-considerations.html shows only KeyNotFound as an event to trigger a replica read, however above this it states "In conditions where access to the active node is unavailable (for example, it is disconnected from the network), an application may be able to access a replica version of the item using the get-from-replica operation which queries a replica node for a copy of the item."
In that case NodeUnavailable would be returned, so there are other cases in which a replica read should be used based on the ResponseStatus that is returned by the SDK.