Might just be a problem on my end but I'm reporting it anyway. Report:
https://paste.dimdev.org/adipumanuc.mccrash

Unterminated object at line 4 column 3 path $.landing_text - check your main book json there is an ending symbol missing in line 4

I added the ending symbol and it still crashed.

New pastebin log? You might have more errors - it will just crash and list the first one it encounters.

https://paste.dimdev.org/suzocezare.mccrash

Unterminated object at line 4 column 2 path $.landing_text - you have another unclosed bracket - might I suggest linking me your book - I'll look at it for you?

book_lol.zip

You need a comma after the landing text ends - .",