2016-11-08 08:53:43.919 iOSRealm[2629:65667] Sync: Connection[1]: Session[1]: Bad changeset received: Assertion failed: left().nullable == right().nullable

private func synchronouslyLogInUser() throws {
    SyncUser.authenticateWithCredential(Credential.usernamePassword(username, password: password, actions:.UseExistingAccount), authServerURL: authURL) { (user, error) in
        print("sent login request")
        if let user = user {
            print("user was not nil")
            self.setDefaultRealmConfiguration(user)
        }
        if let error = error where error.code == SyncError.HTTPStatusCodeError.rawValue && (error.userInfo["statusCode"] as? Int) == 400 {
            print("invalid user and pass")
        } else {
            print(error)
        }
    }
}

private func setDefaultRealmConfiguration(user: SyncUser) {
    Realm.Configuration.defaultConfiguration = Realm.Configuration(syncConfiguration: (user, realmURL), objectTypes: [Weather.self, Wind.self])
    Realm.Configuration.defaultConfiguration.deleteRealmIfMigrationNeeded = true
    realm = try! Realm()
}

class Weather : Object {
    dynamic var id = 0
    dynamic var date = ""
    dynamic var forecast = ""
    dynamic var humidity = ""
    dynamic var wind: Wind!

    override class func primaryKey() -> String? {
        return "id"
    }
}

class Wind: Object {
    dynamic var direction = ""
    dynamic var speed = ""
}

public class Weather extends RealmObject {
    @PrimaryKey
    public int id;
    public String date;
    public String forecast;
    public String humidity;
    public Wind wind;
}

public class Wind extends RealmObject {
    public String direction;
    public String speed;
}

class Weather : Object {
    dynamic var id = 0
    dynamic var date: String?
    dynamic var forecast: String?
    dynamic var humidity: String?
    dynamic var wind: Wind?

    override class func primaryKey() -> String? {
        return "id"
    }
}

class Wind: Object {
    dynamic var direction: String?
    dynamic var speed: String?
}