Koenig - Handle deletion of last card with no other sections
Koenig - Handle deletion of last card with no other sections

refs https://github.com/TryGhost/Ghost/issues/9505
- if there is only a single card in a document and no other text then deleting it would throw an error because we assumed there's another section to move the cursor to
- handle the situation of not having a position to move to by creating a new blank paragraph and placing the cursor inside

kevinansfield/Ghost-Admin,kevinansfield/Ghost-Admin,TryGhost/Ghost-Admin,TryGhost/Ghost-Admin