Adding translation to Content and switching the main language will prevent restored archived version from being published with 500 error.

Steps to reproduce
1. Clean installation of eZ Platform 2.5.1
2. Add a new Language (German, ger-DE).
3. Create a new Article, named Article ENG. Publish it.
4. Go to Article ENG Translations tab, add new German Translation with name Article GER. Publish it.
5. Again in the Article ENG Translations tab change Main language to German.
6. Go to the Versions tab. Inside Archived versions click Restore button next to Version 1 (in English). Publish it.

Result
Version won't be published and ContextErrorException will be thrown, saying:

Notice: Trying to get property 'value' of non-object