React on addon unregistration errors

Author: ros-dorian

mitsuba-blender/__init__.py

@@ -93,8 +93,8 @@ def unregister_addon():
     This may fail if Mitsuba wasn't found, hence the try catch guard
     '''
     try:
-        engine.unregister()
         nodes.unregister()
+        engine.unregister()
         ui.unregister()
         operators.unregister()
         properties.unregister()
@@ -289,7 +289,8 @@ def register():
 def unregister():
     for cls in classes:
         unregister_class(cls)
-    unregister_addon()
+    if not unregister_addon():
+        print('FAILED TO UNREGISTER ADDON')
 
 if __name__ == '__main__':
     register()

mitsuba-blender/nodes/materials/__init__.py

@@ -34,7 +34,7 @@ def register():
         register_class(cls)
 
 def unregister():
-    unregister_node_categories('MITSUBA_MATERIAL_TREE')
-
     for cls in classes:
         unregister_class(cls)
+
+    unregister_node_categories('MITSUBA_MATERIAL_TREE')