Widget does not preview the quiz for users who are not logged in

[nygrenh]

TypeError: y.items is undefined

• Include items in preview endpoint

https://ohjelmointi-21.mooc.fi/osa-1/5-ehtorakenne#quiz-1d2102eb-0c2f-5185-a240-9814db357c8a

[Technopathic]

Here are the steps I took:

1. Logged in (Quiz works fine)
2. Logging out throws y.items is undefined error in Firefox and length undefined in Chrome.
3. Reloading / Cache Clear (Issue is unresolved)

Here is a branch for debugging:
https://elements-of-ai-material-git-quiz-widget-update.mooc.vercel.app/1/1

Scrolling down the page to the quiz and having logged out, the error should be visible.