How to use types inside JSX with collections?

[covert whale]

I'm trying to use:

postEntries.map((post: CollectionEntry<'post'>) => (

but I get:

Unable to assign attributes when using <> Fragment shorthand syntax!
  Hint:
    To fix this, please change < post'> to use the longhand Fragment syntax: <Fragment post'>

[keen tinsel]

I think you need TSX, right?