fix: consistent composer instance properties across scopes

[BobbieGoede]

🔗 Linked issue

• Cannot read properties of undefined (reading 'filter') #3295

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Resolves #3295

The properties on a composer instance changed when using a locale scope, I'm not sure if this was always the case or perhaps this was originally intended to better match legacy vue-i18n type/usage 🤔

📝 Checklist

• I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.

[pkg-pr-new]

Open in Stackblitz

npm i https://pkg.pr.new/@nuxtjs/i18n@3324

commit: af4f31a

[BobbieGoede]

After some investigation, this was likely a regression I introduced when integrating vue-i18n-routing and misunderstanding some of the extend structure, I can't reproduce the inconsistency using 8.0.0.