My goal is to the rest of these little bugs found and squashed before offering a print version (as it is infinitely easy and cheaper to replaced PDFs than books). Once I've committed the book to print, I will put out an updated PDF that has all of this errata in place. For now, I'll keep track of it here.
Warrior Class: The "Indomitable" skill's last sentence should read "At 9th level you may use this feature twice between rests, and at 10th level you may use it thrice between rests."
Druid spell "Conjure Animals": The first line should read "You summon fey spirits that take the form of animals or non-evil beasts and appear in unoccupied spaces that you can see within range" Additionally, instead of the four options given for the amount of creatures that are summoned, there should only be two which are "Two creatures of CR 1" and "Four creatures of CR 0."