When reading the archetype-metadata.xml file, would be helpful to know if the XML was badly formed

If archetype-metadata.xml is malformed, say with a module element which is unclosed (missing slash), there is no error message displayed in the log output, even with the debug(-X) parameter set.

The DefaultArchetypeArtifactManager class contains methods which catch exceptions but do not log the problem. The problem is just silently ignored. I've created a patch file to log the problem at WARN level so that anyone who has a problem can see why it occured.