text: import React, { Component } from 'react'
  
  export default class Callback extends Component {
    componentDidMount(){
      if (/access_token|id_token|error/.test(this.props.location.hash)){
          this.props.auth.handleAuthentication()
      } else {
          throw new Error('Invalid callback URL.')
      }
    }
    
      render() {
      return (
        <h1>
          ...loading
        </h1>
      )
    }
  }
  