From da7ba7b1e9fb8529026b35688f35f5d2c0408b37 Mon Sep 17 00:00:00 2001
From: Dion Moult <dion@thinkmoult.com>
Date: Tue, 23 Jun 2020 22:49:56 +1000
Subject: [PATCH] Fix bug for exporting slots with no materials

---
 src/ifcblenderexport/blenderbim/bim/export_ifc.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ifcblenderexport/blenderbim/bim/export_ifc.py b/src/ifcblenderexport/blenderbim/bim/export_ifc.py
index f5fab7e186..d004fa2584 100644
--- a/src/ifcblenderexport/blenderbim/bim/export_ifc.py
+++ b/src/ifcblenderexport/blenderbim/bim/export_ifc.py
@@ -478,7 +478,7 @@ class IfcParser():
                     obj[key], []).append(product)
 
         for slot in obj.material_slots:
-            if slot.link == 'OBJECT':
+            if slot.material is None or slot.link == 'OBJECT':
                 continue
             if obj.BIMObjectProperties.material_type == 'IfcMaterialLayerSet':
                 self.rel_associates_material_layer_set.setdefault(self.product_index, []).append(