How to disable the back button on certain React Navigation routes with React Native

Question

Hi, I’m working with React Navigation and I’m having problems regarding the "back" button on certain screens.

My Navigator is as follows:

import React from 'react'
import { FluidNavigator } from 'react-navigation-fluid-transitions'

import SplashScreen from '../../screens/SplashScreen'
import LoginScreen from '../../screens/LoginScreen'
import RegisterCodeScreen from '../../screens/RegisterScreen/RegisterCodeScreen'
import RegisterEmailScreen from '../../screens/RegisterScreen/RegisterEmailScreen'
import RegisterInfoScreen from '../../screens/RegisterScreen/RegisterInfoScreen'
import LanScreen from '../../screens/LanScreen'

export default Navigator = FluidNavigator({
  SplashScreen: { screen: SplashScreen },
  LoginScreen: { screen: LoginScreen, },
  RegisterEmailScreen: { screen: RegisterEmailScreen },
  RegisterCodeScreen: { screen: RegisterCodeScreen },
  RegisterInfoScreen: { screen: RegisterInfoScreen },
  LanScreen: { screen: LanScreen }
});

I need to block the "back" only on the screens LoginScreen and LanScreen and for that (at the moment) I am using the resource below:

export defaut class LoginScreen extends React.Component {

  componentDidMount() {
    BackHandler.addEventListener('hardwareBackPress', () => true);
  }

  // ....

}

The problem is that using Backhandler causes it to disable on all routes and I don’t want it... How to solve?