[#D3D-2363] Fixes exception if parent_bone but no parent

exporter/osg/osgbake.py

@@ -211,7 +211,7 @@ def objFrameInfo(blender_object, do_visual_keying):
     # TODO, pass data rather then grabbing from the context!
     scene = bpy.context.scene
     frame_back = scene.frame_current
-    if blender_object.parent_bone:
+    if blender_object.parent_bone and blender_object.parent:
         bone_height = blender_object.parent.data.bones[blender_object.parent_bone].tail_local.z \
             - blender_object.parent.data.bones[blender_object.parent_bone].head_local.z
         bone_correction = Vector((0, bone_height, 0))
@@ -325,7 +325,7 @@ def objFrameInfo(blender_object, do_visual_keying):
             # visual keying is enabled so set parent to identity
             if do_visual_keying:
                 blender_object.matrix_parent_inverse.identity()
-                if blender_object.parent_bone:
+                if blender_object.parent_bone and blender_object.parent:
                     # Blender considers bone's tail instead of bone's head for parenting
                     # so we need to take to take bone's length into account
                     blender_object.location = blender_object.location + bone_correction