[3.10] gh-94360: Fix a tokenizer crash when reading encoded files with syntax errors from stdin (GH-94386) (GH-94574)

Signed-off-by: Pablo Galindo <pablogsal@gmail.com>
Co-authored-by: Pablo Galindo Salgado <Pablogsal@gmail.com>
Co-authored-by: Łukasz Langa <lukasz@langa.pl>

(cherry picked from commit 36fcde61ba48c4e918830691ecf4092e4e3b9b99)