Arch: Enable compression when exporting IFC files (reuse similar vectors, colors, etc)

src/Mod/Material/MaterialEditor.py

@@ -142,10 +142,11 @@ class MaterialEditor:
         self.getMaterialResources()
         self.cards = {}
         for p in self.resources:
-            for f in os.listdir(p):
-                b, e = os.path.splitext(f)
-                if e.upper() == ".FCMAT":
-                    self.cards[b] = p + os.sep + f
+            if os.path.exists(p):
+                for f in os.listdir(p):
+                    b, e = os.path.splitext(f)
+                    if e.upper() == ".FCMAT":
+                        self.cards[b] = p + os.sep + f
         # self.outputCards()
         if self.cards:
             self.widget.ComboMaterial.clear()