Nondescript exception with using the CDI add-on without CDI enabled

[Legioth]

If CDI isn't enabled, ContextDeployer will still be run through the standard @WebListener annotation. This will result in a NPE from AnnotationUtil.getUiBeans caused by the injected beanManager field in ContextDeployer being null.

We should instead check for this in the beginning of ContextDeployer.contextInitialized and either throw a more user friendly exception or alternatively log a clear message and return eagerly without trying to configure any CDI servlets.