Chapter 5 - Snapshot user info - Incorrect error handler

[jrogel]

Hello, looking at the Snapshot user info section in Chapter 5. I believe there is the possibility that the wrong error handler is being used in the from(notification: implementation. I think it should be throwing the error about noUserInfo, ie as follows:

    // 2
    guard let userInfo = notification.userInfo else {
      throw SnapshotError.noUserInfo
    }