wxGUI/iclass: fix iclass launching, broken in https://trac.osgeo.org/grass/changeset/63534

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@64667 15284696-431f-4ddb-bdfa-cd5b030d7da7

gui/wxpython/iclass/frame.py

@@ -431,7 +431,7 @@ class IClassMapFrame(DoubleMapFrame):
 
     def GetMapToolbar(self):
         """Returns toolbar with zooming tools"""
-        return self.toolbars['iClassMap']
+        return self.toolbars['iClassMap'] if 'iClassMap' in self.toolbars else None
 
     def GetClassColor(self, cat):
         """Get class color as string