Fix for minimum needs startup on a fresh machine

Fix issue where traceback is shown when starting on a new computer installation with no previous minimum needs in qsettings.
In my pR #1371 , I fixed this by set the type as `dict` (when retrieve `MinimumNeeds`). And it gives an empty dict (no matter what I put in default value). So, I think it's probably better if we just say:
```python
if not minimum_needs:
    foo
```

I will check it today, anyway