Handle exceptions raised by actions triggered in "inspector" Component when no active Ibl Set is defined.

[KelSolaar]

Stack Trace
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0   <type 'exceptions.AttributeError'>
1   
2   Traceback (most recent call last):
3   .. File "<string>", line 312, in <module>
4   .. File "<string>", line 309, in main
5   .. File "C:/Program Files/HDRLabs/sIBL_GUI 4\umbra\engine.py", line 1864, in run
6   .... return sys.exit(RuntimeGlobals.application.exec_())
7   .. File "C:/Program Files/HDRLabs/sIBL_GUI 4/sibl_gui/components/addons/rawEditingUtilities\rawEditingUtilities.py", line 621, in __inspector_editActiveIblSetFileAction__triggered
8   .... return self.editActiveIblSetFileUi()
9   .. File "C:/Program Files/HDRLabs/sIBL_GUI 4/sibl_gui/components/addons/rawEditingUtilities\rawEditingUtilities.py", line 776, in editActiveIblSetFileUi
10  .... self.__class__.__name__, activeIblSet.title))
11  AttributeError: 'NoneType' object has no attribute 'title'