Converts a NATS message into some other type. Implementers are expected to:
return [err, null] if the message callback is invoked with an error.
return [err, null] if converting the message yielded an error, note that
iterators will stop on the error, but callbacks will be presented with
the error.
return [null, T] if the conversion worked correctly
Converts a NATS message into some other type. Implementers are expected to: return [err, null] if the message callback is invoked with an error. return [err, null] if converting the message yielded an error, note that iterators will stop on the error, but callbacks will be presented with the error. return [null, T] if the conversion worked correctly