This is a follow up for 2b60fe95
## Issues
- Not every page needs the Category data, so only block for Category pages.
- `categoryPages.length` was rendered as a number while blocking for the fetch.
## Change
It's a chicken-and-egg thing because we don't know what the category path is, but fortunately categories and internal pages start with `/$/`, so we can make a reliable guess. The other internal pages would have matched the defined routes and would not reach this function.
f69097b488