FE does not crash when an article without a primary section is referenced in a section list or article list extra
- Article::getPrimarySection() returns a NullSection instead of throwing an exception if there is no primary section
- the extras filter out articles with a NullSection as primary section before passing them to smarty
Nonetheless, articles without a section are an inconsistency and lead to BE malfunctions. they should be further guarded against.
[#2139]