Blank error message returned if you sign out from the account switcher and try to start a timer

[somnolentPumpkin]

Description

When you sign out from the account switching subwindow, the widget doesn't update to show that you're signed out. That means that you're still able to click Start Timer. When you do so, an error box appears without any text. It looks like this:

Steps to reproduce

1. Open a platform widget and make sure you're signed in.
2. Click Switch Account.
3. Instead of selecting an account, click Sign Out at the bottom.
4. Go back to the widget and click Start Timer.

Expected result

Either signing out would update the widget to show the You need to sign in! page again, or at an error would be displayed that says I'm not signed in.