Major Description
Well, for gods sake it fails at least 
Still, a null pointer might not be the best error to show to a user who is quite of glueless what's the problem seeing the null pointer. Instead a MojoFailureException should be thrown (which should be thrown, according to it's jdoc in kind of compilation, built, ... error) which fits fine our situation I think. This won't change the behavior (which is a pretty good one IMHO; at least what do you want to do with an assembly missing half the artifacts), but make the result better to read.