Penggunaan json.parse di function error, kenapa ya ?

Saya berhasil memasukkan data user ke asyncstorage, dan juga berhasil ketika getItem lewat function get. tapi error saat masuk function getData di trace sih karena JSON.parse(this.get()). Itu kenapa ya ?

import {AsyncStorage} from 'react-native';

  export const userHelper = {
  isValidData: function(data) {
    // data is a json object with token, name, and photo
    if(
      typeof data === 'object' &&
      typeof data.token !== 'undefined' &&
      typeof data.u_name !== 'undefined' &&
      typeof data.u_email !== 'undefined' &&
      typeof data.u_photo !== 'undefined'
    )
    return true;
    else
    return false;
  },
  get: async function() {
    // can be used to check if valid data is stored
    try{
      var data = await AsyncStorage.getItem('userProvesty');
      if (data !== null){
        if(data && this.isValidData(JSON.parse(data)))
        return data;
        console.log("hasil get: " + data);
      }
    } catch (err){
      console.log("parsing userHelper get gagal");
    }
  },
  getData: async function(item){
    try{
      var data = await JSON.parse(this.get());
      if(data !== null){
        if(data && typeof(data[item]) !== 'undefined')
        return data[item];
        console.log(data[item]);
      }
    }
    catch(err){
      console.log("error getData")
    }
  },
  isLogin: function(){
     return this.getData('token');
  },
  getToken: function() {
    return this.getData('token');
  }
}

export default userHelper;