Comment 4 for bug 1476072

Hi James, Reading the code, I'm baffled you didn't have issues. But hey-ho.

The two places where the get_system_{prop,mono}_font() functions get called immediately check for the None value and skip trying to set the widget font if it is None.

OK, so I have the fix in my local working repos. I'll push it next time I'm doing code changes and pushing them.