glTF exporter: add check to avoid error when armature is parented to another armature

io_scene_gltf2/__init__.py

@@ -15,7 +15,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (1, 2, 31),
+    "version": (1, 2, 32),
     'blender': (2, 82, 7),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_gather_drivers.py

@@ -27,6 +27,9 @@ def get_sk_drivers(blender_armature):
     for child in blender_armature.children:
         if not child.data:
             continue
+        # child.data can be an armature - which has no shapekeys
+        if not hasattr(child.data, 'shape_keys'):
+	        continue
         if not child.data.shape_keys:
             continue
         if not child.data.shape_keys.animation_data: