fix(cache): remove cached value when revalidation results in an error…

[cjpearson]

… or invalid value

🔗 Linked issue

#1992

❓ 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

When an SWR revalidation occurs the existing value is not initially deleted from the cache storage. Instead it only overwritten after the revalidation is complete. However, if the revalidation results in an error or invalid value, the original value remains in the cache storage. This can result in a stale value persisting in the cache throughout many revalidations, long after it should have been replaced.

Another approach could be to preemptively delete the stored value. This may simplify the implementation, but it means that other requests which arrive during the revalidation will not be served the cached value.

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.