Description:

Can't switch from Aztec to Gutenberg on a post with a title but no content.

Steps to reproduce:

1. Go to app settings and make sure Gutenberg is enabled.
2. Open an existing post with title but no content.
3. Gutenberg should load up, tap on "..." and select "Switch to Classic".
4. Aztec will load up the post, tap on "...".

Notice there's no option to "Switch to Gutenberg", but there should be.

First reported here: #10969 (review)