glTF exporter: fix bug when vertex group index is out of range of existing vertex groups

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, 49),
+    "version": (1, 2, 50),
     'blender': (2, 82, 7),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/blender/exp/gltf2_blender_extract.py

@@ -709,6 +709,9 @@ def extract_primitives(glTF, blender_mesh, blender_object, blender_vertex_groups
                     #
 
                     vertex_group_index = group_element.group
+
+                    if vertex_group_index < 0 or vertex_group_index >= len(blender_vertex_groups):
+                        continue
                     vertex_group_name = blender_vertex_groups[vertex_group_index].name
 
                     joint_index = None