No content or final recap after last exercise

[irnc]

Clicking on Go to Next Lesson from last exercise number 15 reloads page to the same exercise. This link uses Hugo's .NextInSection property, but because there are no more pages, it points to itself.

https://github.com/osmlab/learnoverpass/blob/1585e27ebeef36a98b7110b766fc596661cb9f6a/themes/src/layouts/exercise/single.html#L46

Ideally Go to next lesson should congratulate learner and show final recap of things taught during the course. Maybe with links to next steps, e.g. more advanced courses or documentation for concepts used in the course.