Fix bug caused by empty config.json

[sestinj]

Description

Users who had an empty or invalid config.json were seeing an error loading the config because the migration was failing, but this isn't a critical error so it just needs to be logged instead of blocking all usage

Checklist

• [x] I've read the contributing guide
• [x] The relevant docs, if any, have been updated or created
• [x] The relevant tests, if any, have been updated or created