Decided to try the beta build of WP 5.0 today to get a feel for Gutenberg block development, but it's not building confidence. Following the examples in the Handbook (Link: https://wordpress.org/gutenberg/...) and it's failing when trying to set up the rich text editor because apparently the object it relies upon is undefined. Been trying to track down the code for the basic paragraph box for an hour or so now so I can see how it's doing things, and haven't turned up anything useful.