Why leapp preupgrade fails with error "ParseError: no element found: line 1, column 0" ?

Issue

• Leapp preupgrade fails with below error :

Risk Factor: high (error)
Title: Actor firewalld_facts_actor unexpectedly terminated with exit code: 1
Summary: Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/leapp/repository/actor_definition.py", line 74, in _do_run
    actor_instance.run(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/leapp/actors/__init__.py", line 289, in run
    self.process(*args)
  File "/usr/share/leapp-repository/repositories/system_upgrade/el7toel8/actors/firewalldfactsactor/actor.py", line 33, in process
    tree = ElementTree.parse('/etc/firewalld/direct.xml')
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 1182, in parse
    tree.parse(source, parser)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 657, in parse
    self._root = parser.close()
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 1654, in close
    self._raiseerror(v)
  File "/usr/lib64/python2.7/xml/etree/ElementTree.py", line 1506, in _raiseerror
    raise err
ParseError: no element found: line 1, column 0