Setting up an empty default handler is not only useless, but actually
harmful, since internal entity-references are not resolved anymore.
From the libexpat docs[1]:
| Setting the handler with this call has the side effect of
| turning off expansion of references to internally defined general
| entities. Instead these references are passed to the default
| handler.
[1] <https://www.xml.com/pub/1999/09/expat/reference.html#setdefhandler>