A Word For A Typographical Illusion or Typo Blindness?
The specific illusion would probably fall under Future Perception, where the second "the" is consumed as we have already guessed what will come next. https://en.wikipedia.org/wiki/Optical_illusion#Future_perception
A term I have seen for this specific occurrence concerning written text, is Typoglycemia. -- It does have an urban dictionary entry, so take it for what you will.
https://en.wikipedia.org/wiki/Typoglycemia