BUG: Facet block doesn't render anything on frontend for single post

[burhandodhy]

Describe the bug

Facet block doesn't render anything on the frontend for the single post , but it does render the result in the post edit screen.

Steps to Reproduce

1. Add Facet block in new post.
2. The block does render the render in the edit screen but not on the frontend.

[felipeelia]

We should probably prevent people from adding that block on single posts/pages, as it doesn't make much sense to facet anything there.