Fix error with empty module table (#328)

modules/gui/module.lua

@@ -307,6 +307,9 @@ Event.add(defines.events.on_entity_settings_pasted, function(event)
         end
 
         clear_module(player, destination.bounding_box, destination.name)
+
+        if next(source_inventory_content) ~= nil then
             apply_module(player, destination.bounding_box, destination.name, {['n']=source_inventory_content, ['p']=source_inventory_content})
         end
+    end
 end)