Blocking GetAccount example is ambiguous

Game Design
1 
if err := initializer.RegisterBeforeGetAccount(func(ctx context.Context, logger runtime.Logger, db *sql.DB, nk runtime.NakamaModule) error {
    return nil
  }); err != nil {
    return err
  }

The above code is provided as an example to disable the GetAccount API call from the client side. However, in a successful case as well, the endpoint would return a nil in the response as only error type is accepted as the return.

How is disabling distinguished from a successful BeforeGetAccount hook?

Ref: L52 on Nakama: Guarding APIs | Heroic Labs Documentation