Fix issue packing lamps with non-IES 'storage'

Lamp/light nodes might have a `storage` property that might point to an
IES texture node (which has the expected `filepath`), but not always.
The latter now no longer crashes BAT.

This fixes https://projects.blender.org/blender/blender-asset-tracer/pulls/92883

CHANGELOG.md

@@ -5,6 +5,8 @@ changed functionality, fixed bugs).
 
 # Version 1.17 (in development)
 
+- Fix issue packing lamps with non-IES 'storage' (File as Flamenco [issue #104269](https://projects.blender.org/studio/flamenco/issues/104269)).
+
 # Version 1.16 (2023-11-02)
 
 - Add `BlendFileBlock.raw_data()` and `.as_string()` functions. These functions interpret the data in a `BlendFileBlock` as either `bytes` or `string`. This can be used to obtain the contents of a `char*` (instead of the more common embedded `char[N]` array).

blender_asset_tracer/trace/blocks2assets.py

@@ -226,5 +226,11 @@ def lamp(block: blendfile.BlendFileBlock) -> typing.Iterator[result.BlockUsage]:
         storage = node.get_pointer(b"storage")
         if not storage:
             continue
-        path, field = storage.get(b"filepath", return_field=True)
+
+        # A storage block of `NodeShaderTexIES` type has a `filepath`, but not
+        # all types that can be pointed to by the `storage` pointer do.
+        path, field = storage.get(b"filepath", return_field=True, default=None)
+        if path is None:
+            continue
+
         yield result.BlockUsage(block, path, path_full_field=field)