使用されていないバッファがあった場合は警告を表示し、途中で落ちないよう修正

python/src/nnabla/utils/converter/onnx/reader.py

@@ -394,7 +394,14 @@ def onnx_graph_to_nnp_protobuf(pb, graph):
             # This input is a variable
             v.type = var_type_buffer
             in_list.append(v)
-        del all_vars[v.name]
+        if v.name in all_vars:
+            del all_vars[v.name]
+        else:
+            # We come here when a buffer (usually a parameter) is included in
+            # graph.input and graph.initializer,
+            # but was not actually used as input for any node.
+            # No one is using this buffer so we show a warning and ignore it.
+            logger.warning("Input buffer {} is not used as input for any node.".format(v.name))
     for o in graph.output:
         v = onnx_value_info_proto_to_variable(o, network)
         v.type = var_type_buffer

python/test/utils/test_conversion.py

@@ -337,10 +337,6 @@ def test_onnx_nnp_conversion_resnet50(tmpdir, nnp_fixture):
     if show_onnx:
         print(model)
     img = np.random.rand(1, 3, 224, 224).astype(np.float32)
-    # Remove an unused buffer with the name of
-    # 'gpu_0/imagenet1k_blobs_queue_f22e83c9-22cd-4a8b-a66d-113af6b832b4_0'
-    del model.graph.input[-1]
-    del model.graph.initializer[-1]
     # Remove Softmax and Gemm for now.
     # This is temporal
     nodes = len(model.graph.node)