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()
}