In the book, at the bottom right, there are the “discuss” and “report erratum” links, pointing to:
- discuss: http://forums.pragprog.com/forums/jbtracer
- report erratum: http://pragprog.com/titles/jbtracer/errata/add
The “discuss” link is broken; it’s redirected to https://pragprog.com
The “report erratum” link is not strictly broken, but not exact either - it points to the book page (https://pragprog.com/titles/jbtracer/the-ray-tracer-challenge), but the errata page, which is mentioned in such page, is actually https://devtalk.com/books/the-ray-tracer-challenge.