I disagree with anyone who claims the WT pubs contain no errrors.
If you run watchtower publications - especially older ones - through a spell-checker, you will be surprised at the number of misspellings and double word, e.g., "the the" that occur. The thing is that few people have the opportunity to do that. When we read a page with erros in it, many times our mind compensates for the error unless it is glaring.
Not so with text "read" by a machine. With the proliferation of digital libraries of WT publications (both official and unofficial) , you can check this for yourself.
They're not as perfect as they'd have you believe they are.