From 472e6e88c3ed498e4cd2e93c0bda16171388e164 Mon Sep 17 00:00:00 2001
From: Lipu Fei <lipu.fei815@gmail.com>
Date: Thu, 19 Sep 2019 14:39:03 +0200
Subject: [PATCH] Fix typing

---
 plugins/MachineSettingsAction/MachineSettingsAction.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/plugins/MachineSettingsAction/MachineSettingsAction.py b/plugins/MachineSettingsAction/MachineSettingsAction.py
index 25586ddeb0..28535024a7 100755
--- a/plugins/MachineSettingsAction/MachineSettingsAction.py
+++ b/plugins/MachineSettingsAction/MachineSettingsAction.py
@@ -60,6 +60,8 @@ class MachineSettingsAction(MachineAction):
     #   flavour setting is changed.
     def _updateHasMaterialsInContainerTree(self) -> None:
         global_stack = cura.CuraApplication.CuraApplication.getInstance().getGlobalContainerStack()
+        if global_stack is None:
+            return
         machine_node = ContainerTree.getInstance().machines[global_stack.definition.getId()]
 
         if machine_node.has_materials != parseBool(global_stack.getMetaDataEntry("has_materials")):  # May have changed due to the g-code flavour.