Describe the bug

I have enabled i18n for content authoring. I believe I should be able to save a post in the primary language without adding all the translations at the same time. When I try to save, I get no visible error. Instead, I get this error in the console.

To Reproduce

0. On a site configured as my config linked below
1. Go to /admin
2. Click on 'New Blog Post'
3. Complete the form for the English post
4. Try and click on 'Save'
5. See error in console

Expected behavior

0. On a site configured as my config linked below
1. Go to /admin
2. Click on 'New Blog Post'
3. Complete the form for the English post
4. Try and click on 'Save'
5. Saves only the translation you've created

Screenshots

Applicable Versions:

• Netlify CMS: 2.10.63
• Git provider: GitHub
• OS: Mac
• Browser version: Version 86.0.4240.80 (Official Build) (x86_64)

CMS configuration

https://github.com/Nexmo/deved-platform/blob/i18n-netlify-cms/static/admin/config.yml

Additional context

If I complete all the fields for all the languages, it then lets me save!