Hi!
Great book so far, I’m learning a lot! 
The errata I found is at page 136, right when we are creating the promo LiveView. We are instructed to create a live view (promo_live.ex) with a .header and a .simple_form. Then, we are shown a picture of what we should see: the title and the subtitle, but no form. Furthermore, if we go to /promo we see an error because @form is not yet initialised at this point.
Removing the .simple_form from the first excerpt of code would fix this. It is not a big deal because it gets fixed when you code the next instructions (the mount fn and so on). Still, just so you know.
Thanks!
Pere