Error while performing certain requests on the Search resources REST API

Steps to reproduce:

1. Login as an Admin
2. Go to the Global Administration: Localization page
3. Set multilingual to yes and add French as a supported language
4. Go to the Global Administration: Search page
5. Set the Indexing Action to "reindex" and hit Apply
6. Wait for the indexing to be completed
7. Perform this request: http://localhost:8080/xwiki/rest/wikis/query/?q=locale:fr&limit=10&media=json (your server address / port may vary)

Expected result:

A json response with a list of pages translated in french

Actual result:

A 500 error.