This default case only means that, according to the spec, that this type of error does not have any auxiliary data, not that we don't know how to handle it. For example,  `errUnauthorized` doesn't have any other data except the code the message.

You could have another case statement however and like so:
```
case errUnauthorized, errServer, etc, etc:
    return errD
default:
    log("Unknown error!")
    return errD
```

However I don't think this is particularly useful as all the errors are explicitly documented in the binary protocol documentation, and if we did get an error that wasn't it might mean we have other dire problems.