live news pages in our fixtures have a list index out of range

## Describe the bug

"list index out of range"

4:41
I think its a problem with
4:41
"node": {
"pageType": "news page",
"janisUrls": [
"/mvp-news-aph/mvp-news-by-cpio-for-aph/"
],
"janisInstances": null
}
4:41
this news page, the janisInstances is null, should be [ ]. so somehwhere in there its trying to janisUrl[0] something that is empty

## URL

https://joplin-pr-4504-doc-migration.herokuapp.com/admin/pages/search/?q=&content_type=news_page.newspage

page id 435 & 437. If they are live then get all pages has an issue. I believe its somethign to do with the janisUrls[0] in the janis instances in the schema

## To Reproduce
Steps to reproduce the behavior
example:
1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

## Current behavior
A clear and concise description of what happened

## Expected behavior
A clear and concise description of what you expected to happen

## Screenshots

## Device and browser

## Additional context

Start by examining the live news-page fixtures and the schema fields janisUrls and janisInstances, then reproduce the failure through the admin pages search URL for page IDs 435 and 437. Done means live news pages and “get all pages” no longer produce “list index out of range” when janisInstances is null.

Written by the indexing model from the issue text.