[Bf-extensions-cvs] [b665525d] blender-v3.4-release: glTF exporter: fix crash with weird missing datablock node group

[Julien Duroure]

Commit: b665525d03ce2a58084375ac61f07c0682568965
Author: Julien Duroure
Date:   Mon Nov 28 15:20:48 2022 +0100
Branches: blender-v3.4-release
https://developer.blender.org/rBAb665525d03ce2a58084375ac61f07c0682568965

glTF exporter: fix crash with weird missing datablock node group

===================================================================

M	io_scene_gltf2/__init__.py
M	io_scene_gltf2/blender/exp/gltf2_blender_get.py

===================================================================

diff --git a/io_scene_gltf2/__init__.py b/io_scene_gltf2/__init__.py
index 103bd0dc..0b9664e8 100755
--- a/io_scene_gltf2/__init__.py
+++ b/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, 4, 48),
+    "version": (3, 4, 49),
     'blender': (3, 3, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',
diff --git a/io_scene_gltf2/blender/exp/gltf2_blender_get.py b/io_scene_gltf2/blender/exp/gltf2_blender_get.py
index 9e468186..dacfbf4a 100755
--- a/io_scene_gltf2/blender/exp/gltf2_blender_get.py
+++ b/io_scene_gltf2/blender/exp/gltf2_blender_get.py
@@ -96,8 +96,10 @@ def get_socket_old(blender_material: bpy.types.Material, name: str):
     """
     gltf_node_group_names = [get_gltf_node_name().lower(), get_gltf_node_old_name().lower()]
     if blender_material.node_tree and blender_material.use_nodes:
+        # Some weird node groups with missing datablock can have no node_tree, so checking n.node_tree (See #1797)
         nodes = [n for n in blender_material.node_tree.nodes if \
             isinstance(n, bpy.types.ShaderNodeGroup) and \
+            n.node_tree is not None and
             (n.node_tree.name.startswith('glTF Metallic Roughness') or n.node_tree.name.lower() in gltf_node_group_names)]
         inputs = sum([[input for input in node.inputs if input.name == name] for node in nodes], [])
         if inputs: