Error serializing on homepage and 404 on slug pages in cms-prismic example

Bug report

Describe the bug

Viewing of vanilla prismic example works fine on homepage but returns a 404 whenever navigating to slug pages. preview mode also returns this

To Reproduce

Steps to reproduce the behavior, please provide code snippets or a repository:

1. Clone cms-prismic example
2. Add env variables
3. yarn install && yarn dev / now dev
4. Navigate to any post

Expected behavior

Preview not working Live example allows viewing of blog post. (Currently password protected)

Screenshots

System information

• OS: macOS
• Browser: Chrome and Edge (Chromium)
• Version of Next.js: 9.2.3-canary.26 but also tried 9.4
• Version of Node.js: v10.16.3
• prismic-javascript: 2.7.1

Additional context

When trying to integrate with latest packages from npm and Typescript there is an additional error related to the preview.

Error: Error serializing `.preview` returned from `getStaticProps` in "/".
Reason: `undefined` cannot be serialized as JSON. Please use `null` or omit this value all together.

Setting preview = null in getStaticProps removes this but the slug pages still return 404’s.

[b-bot]

@chibicode I have since switched to the Sanity example and it’s working perfectly (what a great platform). However I did check and the slugs were being returned.

@ismamz was correct, it was defaulting to en-us but my Prismic settings geolocated me to en-gb. The strange thing is the posts on the homepage were fine, but only when using yarn dev not with now dev. Submitted PR so this doesn’t happen to anyone else. #12862

As the examples evolve might want to put some fail safes in place as this was breaking in production too.

Thanks for the help guys. Still gonna stick with Sanity.

[balazsorban44]

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