glTF exporter: avoid crash when all drivers are invalids

io_scene_gltf2/__init__.py

@@ -4,7 +4,7 @@
 bl_info = {
     'name': 'glTF 2.0 format',
     'author': 'Julien Duroure, Scurest, Norbert Nopper, Urs Hanselmann, Moritz Becher, Benjamin Schmithüsen, Jim Eckerlein, and many external contributors',
-    "version": (3, 3, 18),
+    "version": (3, 3, 19),
     'blender': (3, 3, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_gather_drivers.py

@@ -74,7 +74,8 @@ def get_sk_drivers(blender_armature_uuid, export_settings):
             else:
                 all_sorted_channels.append(existing_idx[i])
 
-        if len(all_sorted_channels) > 0:
+        # Checks there are some driver on SK, and that there is not only invalid drivers
+        if len(all_sorted_channels) > 0 and not all([i is None for i in all_sorted_channels]):
             drivers.append((child_uuid, tuple(all_sorted_channels)))
 
     return tuple(drivers)