Like any piece of software, liblx has bugs.  It contains various
internal checks, checks which should never trip; if one of them does
trip, liblx calls lx_abort().  This is an odd case for an API: it is an
API-defined routine which the application can, optionally, provide.  If
the application defines lx_abort, liblx will call that version; if not,
it will call an internal version, which simply calls abort(3).

lx_abort() should not return.  If it ever does, the library tries to do
something reasonable, but no promises are made about precisely what; by
their nature, handling can't-happen errors cannot be made precise.  The
interface is provided for applications that want to do some emergency
closedown actions before crashing in case liblx bugchecks.