You can find the full source code for this website in the Seam package in the directory /examples/wiki. It is licensed under the LGPL.
Weld logs what beans it creates and deploys, and any errors loading classes, at debug level. You can view these errors by ensuring that debug logging is enabled. For example, on JBoss AS, start it with:
./run.sh -Djboss.server.log.threshold=DEBUG
to enable debug logging in server/default/log/server.log.