Sample angular app doesn't work

I tried sample angular app doesn’t work.
Once I login with google account, " You are logged in!" message is shown once,
But once I refresh page, a message below is shown.
“Could not get a new token (login_required: Login required).”

Would you give me some advice?

Can you let us know what sample app you’re referring to (including the link, etc.) and also include any code showing your authentication process (minus any sensitive details)? Also do you have any errors in the console.log?