Override replaceContainer and add some type checking

type in this case being container type

Contributes to CURA-3497

cura/Settings/GlobalStack.py

@@ -10,6 +10,7 @@ from UM.Settings.ContainerStack import ContainerStack, InvalidContainerStackErro
 from UM.Settings.InstanceContainer import InstanceContainer
 from UM.Settings.DefinitionContainer import DefinitionContainer
 from UM.Settings.ContainerRegistry import ContainerRegistry
+from UM.Settings.Interfaces import ContainerInterface
 
 from . import Exceptions
 
@@ -121,6 +122,18 @@ class GlobalStack(ContainerStack):
     def removeContainer(self, index: int) -> None:
         raise Exceptions.InvalidOperationError("Cannot remove a container from Global stack")
 
+    ##  Overridden from ContainerStack
+    @override(ContainerStack)
+    def replaceContainer(self, index: int, container: ContainerInterface, postpone_emit: bool = False) -> None:
+        expected_type = _ContainerIndexes.IndexTypeMap[index]
+        if expected_type == "definition" and not isinstance(container, DefinitionContainer):
+            raise Exceptions.InvalidContainerError("Cannot replace container at index {index} with a container that is not a DefinitionContainer".format(index = index))
+        if container != self._empty_instance_container and container.getMetaDataEntry("type") != expected_type:
+            raise Exceptions.InvalidContainerError("Cannot replace container at index {index} with a container that is not of {type} type".format(index = index, type = expected_type))
+
+        super().replaceContainer(index, container, postpone_emit)
+
+    ##  Overridden from ContainerStack
     @override(ContainerStack)
     def deserialize(self, contents: str) -> None:
         super().deserialize(contents)
@@ -152,17 +165,18 @@ class GlobalStack(ContainerStack):
 
         self._containers = new_containers
 
-## private:
 
+## private:
 global_stack_mime = MimeType(
     name = "application/x-cura-globalstack",
     comment = "Cura Global Stack",
-    suffixes = [ "global.cfg" ]
+    suffixes = ["global.cfg"]
 )
 
 MimeTypeDatabase.addMimeType(global_stack_mime)
 ContainerRegistry.addContainerTypeByName(GlobalStack, "global_stack", global_stack_mime.name)
 
+
 class _ContainerIndexes:
     UserChanges = 0
     QualityChanges = 1