glTF exporter: fix crash when armature action is linked to mesh object

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, 1, 13),
+    "version": (1, 1, 14),
     'blender': (2, 81, 6),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_gather_animation_channels.py

@@ -94,6 +94,11 @@ def __get_channel_group_sorted(channels: typing.Tuple[bpy.types.FCurve], blender
         first_channel = channels[0]
         object_path = get_target_object_path(first_channel.data_path)
         if object_path:
+            if not blender_object.data.shape_keys:
+                # Something is wrong. Maybe the user assigned an armature action
+                # to a mesh object. Returning without sorting
+                return channels
+
             # This is shapekeys, we need to sort channels
             shapekeys_idx = {}
             cpt_sk = 0