glTF importer: Show specific error when buffer resource is missing

io_scene_gltf2/__init__.py

@@ -15,7 +15,7 @@
 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": (1, 5, 8),
+    "version": (1, 5, 9),
     'blender': (2, 91, 0),
     'location': 'File > Import-Export',
     'description': 'Import-Export as glTF 2.0',

io_scene_gltf2/io/imp/gltf2_io_gltf.py

@@ -161,8 +161,10 @@ class glTFImporter():
 
         if buffer.uri:
             data = self.load_uri(buffer.uri)
-            if data is not None:
-                self.buffers[buffer_idx] = data
+            if data is None:
+                raise ImportError("Missing resource, '" + buffer.uri + "'.")
+            self.buffers[buffer_idx] = data
+
 
         else:
             # GLB-stored buffer