line 40 and 59, res.render('pug' . I don’t see you have a file named pug.pug in ./views/pug.
res.render’s first argument is a file name (without extension, e.g. res.render('chat', ....
I might be wrong though.
It should be index with that setup or you can comment out the app.set('views', './views/pug') and render pug (which should pick the index file).
I think it is because the challenge that had you set up the Template Engine didn’t expect you to use app.set but res.render and that code is then moved inside the DB connection function and the first argument is changed.
Set up Template Engine https://gist.github.com/camperbot/3515cd676ea4dfceab4e322f59a37791
Implement the Serialization of a Passport User https://gist.github.com/camperbot/175f2f585a2d8034044c7e8857d5add7