We will soon be converting $wgUser to be a stub
object wrapping a User, and we want to be able
to access the public properties of that object
(doing so will still trigger deprecation warnings,
but it won't break). This will also work for
non-existent properties that are handled via
the __get() and __set() methods of whatever
inner object the StubObject is wrapping.
Bug: T267861
Change-Id: I4c29c615bcb107d4ef8bf4b8e48db2ecf863e5f7
