Execute if anything is written in a writable_book

I want to execute if the players selected item (which is a writable book) has any writing in it. With no writing the book has no writable_book_content component so I was thinking I could use that but not sure how to execute if a component is missing. I was thinking something like this but doesn't seem to work... execute if entity @s[nbt={SelectedItem:{id:"minecraft:writable_book", components:{"!minecraft:writable_book_content":{}}}}] run say hi