Fail task instead of skipping if repository name is not set

[Vampire]

If the plugin is applied and the task is called, it is most likely the case that work should be done.
So it might be better in this case to fail the build with a meaningful error instead of silently skipping the task.

If not, then please at least add some logging, at least on info level that explains why the task is skipped.
Currently you are a bit lost if the task is simply skipped.