Ah, that's really cool about Zorro! I really like all the LIs, so it's not only him I'm looking forward to. :)
Don't worry about it. The exception occurred when I clicked on the codex before I'm supposed to / when the game had not told me about the feature yet (I got a habit to click on available buttons on a screen to see what they do).
NameError: name 'codexword_unlocked_number' is not defined