From c21c9c24f865dd18c4d9be5b1130f75af3eec13b Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Tue, 17 Sep 2019 11:20:22 +1000
Subject: [PATCH] Handle materials which don't have nodes

---
 src/ifcblenderexport/export.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/src/ifcblenderexport/export.py b/src/ifcblenderexport/export.py
index bb2fb6963a..f9ba20f24f 100644
--- a/src/ifcblenderexport/export.py
+++ b/src/ifcblenderexport/export.py
@@ -919,7 +919,8 @@ class IfcExporter():
         return self.file.create_entity('IfcSurfaceStyleRendering', **rendering_attributes)
 
     def get_rendering_attributes(self, material):
-        if 'Principled BSDF' not in material.node_tree.nodes:
+        if not hasattr(material.node_tree, 'nodes') \
+            or 'Principled BSDF' not in material.node_tree.nodes:
             return {}
         bsdf = material.node_tree.nodes['Principled BSDF']
         return {