Data pane demo fails to execute

[genedan]

Traceback (most recent call last):
  File "/usr/lib/python3.10/code.py", line 90, in runcode
    exec(code, self.locals)
  File "<input>", line 9, in <module>
  File "/home/ubuntu/FASLR/faslr/data.py", line 133, in __init__
    self.data_model = ProjectDataModel(parent=self)
  File "/home/ubuntu/FASLR/faslr/data.py", line 849, in __init__
    fc = FaslrConnection(db_path=self.parent.main_window.db)
AttributeError: 'NoneType' object has no attribute 'db'

These demos should work out of the box. Current plan would be to amend the demo to launch the sample db and use that as the backend. This should not interfere or delete any databases the user may have already created, so some code should check for that as well.