No idea if this is a correct fix.

Even with the previous fix I still got the following exception:
```
Traceback (most recent call last):
[...]
File "[...]/sdm/oor/plugins/module_utils/sdm_role.py", line 227, in _load_role_data
    self._load_role_tasks(tasks_name=self._from_files.get('tasks'), on_init=True)
  File "[...]/sdm/oor/plugins/module_utils/sdm_role.py", line 260, in _load_role_tasks
    task_data.extend(self._load_role_tasks_yaml(main=tasks_name))
AttributeError: 'NoneType' object has no attribute 'extend'
```

This is probably due to a file getting loaded being empty or
containing just a marker (`---`) and comments.