Bug in Source Profile selection in Advanced Gamut Options dialog

[eoyilmaz]

From the Profiling -> Profiling Type -> Advanced... opens the Advanced Gamut Options dialog.

When an item is selected from the "Source profile" combo box the following error message is thrown:

NoneType: None
┌──────────────────────────────────────────────────────────────────────────────┐
│ Traceback (most recent call last):                                           │
│   File                                                                       │
│ "/Users/eoyilmaz/Documents/development/displaycal-py3/DisplayCAL/wxwindows.py", │
│ line 3233, in OnChanged                                                      │
│     self.changeCallback(evt)                                                 │
│   File                                                                       │
│ "/Users/eoyilmaz/Documents/development/displaycal-py3/DisplayCAL/display_cal.py", │
│ line 1512, in gamap_profile_handler                                          │
│     src_viewcond in [None].extend(self.viewconds_out_nondisplay)             │
│ TypeError: argument of type 'NoneType' is not iterable                       │
└──────────────────────────────────────────────────────────────────────────────┘