CuraContainerStack now overrides getBottom, so it always returns a definition

cura/Settings/CuraContainerStack.py

@@ -254,6 +254,10 @@ class CuraContainerStack(ContainerStack):
     def definition(self) -> DefinitionContainer:
         return self._containers[_ContainerIndexes.Definition]
 
+    @override(ContainerStack)
+    def getBottom(self) -> "DefinitionContainer":
+        return self.definition
+
     ##  Check whether the specified setting has a 'user' value.
     #
     #   A user value here is defined as the setting having a value in either

cura/Settings/MachineManager.py

@@ -33,6 +33,7 @@ from typing import TYPE_CHECKING, Optional
 
 if TYPE_CHECKING:
     from UM.Settings.DefinitionContainer import DefinitionContainer
+    from cura.Settings.GlobalStack import GlobalStack
 
 import os
 
@@ -42,7 +43,7 @@ class MachineManager(QObject):
         super().__init__(parent)
 
         self._active_container_stack = None     # type: ContainerStack
-        self._global_container_stack = None     # type: ContainerStack
+        self._global_container_stack = None     # type: GlobalStack
 
         self._error_check_timer = QTimer()
         self._error_check_timer.setInterval(250)