Allow getContainer() to return None

And in the rest of the locations we must then check if it's None and handle that gracefully.
Here we assume that the getContainer message shows a message to the user if necessary. For now we'll just log it.

Contributes to issue CURA-5045.

cura/Machines/ContainerNode.py

@@ -30,9 +30,10 @@ class ContainerNode:
     def getChildNode(self, child_key: str) -> Optional["ContainerNode"]:
         return self.children_map.get(child_key)
 
-    def getContainer(self) -> "InstanceContainer":
+    def getContainer(self) -> Optional["InstanceContainer"]:
         if self.metadata is None:
-            raise RuntimeError("Cannot get container for a ContainerNode without metadata")
+            Logger.log("e", "Cannot get container for a ContainerNode without metadata.")
+            return None
 
         if self.container is None:
             container_id = self.metadata["id"]
@@ -40,7 +41,8 @@ class ContainerNode:
             from UM.Settings.ContainerRegistry import ContainerRegistry
             container_list = ContainerRegistry.getInstance().findInstanceContainers(id = container_id)
             if not container_list:
-                raise RuntimeError("Failed to lazy-load container [%s], cannot find it" % container_id)
+                Logger.log("e", "Failed to lazy-load container [{container_id}]. Cannot find it.".format(container_id = container_id))
+                return None
             self.container = container_list[0]
 
         return self.container

cura/Machines/MaterialManager.py

@@ -423,6 +423,7 @@ class MaterialManager(QObject):
             return
 
         material_group = self.getMaterialGroup(root_material_id)
+        if material_group:
             material_group.root_material_node.getContainer().setName(name)
 
     #
@@ -447,6 +448,8 @@ class MaterialManager(QObject):
             return None
 
         base_container = material_group.root_material_node.getContainer()
+        if not base_container:
+            return None
 
         # Ensure all settings are saved.
         self._application.saveSettings()
@@ -466,6 +469,8 @@ class MaterialManager(QObject):
         # Clone all of them.
         for node in material_group.derived_material_node_list:
             container_to_copy = node.getContainer()
+            if not container_to_copy:
+                continue
             # Create unique IDs for every clone.
             new_id = new_base_id
             if container_to_copy.getMetaDataEntry("definition") != "fdmprinter":

cura/Machines/Models/QualitySettingsModel.py

@@ -90,7 +90,7 @@ class QualitySettingsModel(ListModel):
             quality_node = quality_group.nodes_for_extruders.get(str(self._selected_position))
         settings_keys = quality_group.getAllKeys()
         quality_containers = []
-        if quality_node is not None:
+        if quality_node is not None and quality_node.getContainer() is not None:
             quality_containers.append(quality_node.getContainer())
 
         # Here, if the user has selected a quality changes, then "quality_changes_group" will not be None, and we fetch
@@ -100,7 +100,7 @@ class QualitySettingsModel(ListModel):
                 quality_changes_node = quality_changes_group.node_for_global
             else:
                 quality_changes_node = quality_changes_group.nodes_for_extruders.get(str(self._selected_position))
-            if quality_changes_node is not None:  # it can be None if number of extruders are changed during runtime
+            if quality_changes_node is not None and quality_changes_node.getContainer() is not None:  # it can be None if number of extruders are changed during runtime
                 try:
                     quality_containers.insert(0, quality_changes_node.getContainer())
                 except RuntimeError:

cura/Machines/QualityManager.py

@@ -393,6 +393,8 @@ class QualityManager(QObject):
             new_name = self._container_registry.uniqueName(quality_changes_name)
             for node in quality_changes_group.getAllNodes():
                 container = node.getContainer()
+                if not container:
+                    continue
                 new_id = self._container_registry.uniqueName(container.getId())
                 self._container_registry.addContainer(container.duplicate(new_id, new_name))
 

cura/Settings/ContainerManager.py

@@ -98,6 +98,7 @@ class ContainerManager(QObject):
             entry_value = root
 
         container = material_group.root_material_node.getContainer()
+        if container is not None:
             container.setMetaDataEntry(entry_name, entry_value)
             if sub_item_changed: #If it was only a sub-item that has changed then the setMetaDataEntry won't correctly notice that something changed, and we must manually signal that the metadata changed.
                 container.metaDataChanged.emit(container)
@@ -377,6 +378,7 @@ class ContainerManager(QObject):
         # NOTE: We only need to set the root material container because XmlMaterialProfile.setMetaDataEntry() will
         # take care of the derived containers too
         container = material_group.root_material_node.getContainer()
+        if container is not None:
             container.setMetaDataEntry("GUID", new_guid)
 
     ##  Get the singleton instance for this class.
@@ -466,5 +468,5 @@ class ContainerManager(QObject):
         if not path:
             return
 
-        container_list = [n.getContainer() for n in quality_changes_group.getAllNodes()]
+        container_list = [n.getContainer() for n in quality_changes_group.getAllNodes() if n.getContainer() is not None]
         self._container_registry.exportQualityProfile(container_list, path, file_type)

cura/Settings/CuraStackBuilder.py

@@ -44,6 +44,8 @@ class CuraStackBuilder:
         global_variant_node = variant_manager.getDefaultVariantNode(machine_definition, VariantType.BUILD_PLATE)
         if global_variant_node:
             global_variant_container = global_variant_node.getContainer()
+        if not global_variant_container:
+            global_variant_container = application.empty_variant_container
 
         # get variant container for extruders
         extruder_variant_container = application.empty_variant_container
@@ -51,6 +53,8 @@ class CuraStackBuilder:
         extruder_variant_name = None
         if extruder_variant_node:
             extruder_variant_container = extruder_variant_node.getContainer()
+            if not extruder_variant_container:
+                extruder_variant_container = application.empty_variant_container
             extruder_variant_name = extruder_variant_container.getName()
 
         generated_name = registry.createUniqueName("machine", "", name, machine_definition.getName())
@@ -72,7 +76,7 @@ class CuraStackBuilder:
         # get material container for extruders
         material_container = application.empty_material_container
         material_node = material_manager.getDefaultMaterial(new_global_stack, extruder_variant_name)
-        if material_node:
+        if material_node and material_node.getContainer():
             material_container = material_node.getContainer()
 
         # Create ExtruderStacks
@@ -107,8 +111,10 @@ class CuraStackBuilder:
         quality_group = quality_group_dict.get(preferred_quality_type)
 
         new_global_stack.quality = quality_group.node_for_global.getContainer()
+        if not new_global_stack.quality:
+            new_global_stack.quality = application.empty_quality_container
         for position, extruder_stack in new_global_stack.extruders.items():
-            if position in quality_group.nodes_for_extruders:
+            if position in quality_group.nodes_for_extruders and quality_group.nodes_for_extruders[position].getContainer():
                 extruder_stack.quality = quality_group.nodes_for_extruders[position].getContainer()
             else:
                 extruder_stack.quality = application.empty_quality_container

cura/Settings/MachineManager.py

@@ -987,6 +987,12 @@ class MachineManager(QObject):
         self.activeQualityChangesGroupChanged.emit()
 
     def _setQualityGroup(self, quality_group, empty_quality_changes = True):
+        if quality_group.node_for_global.getContainer() is None:
+            return
+        for node in quality_group.nodes_for_extruders.values():
+            if node.getContainer() is None:
+                return
+
         self._current_quality_group = quality_group
         if empty_quality_changes:
             self._current_quality_changes_group = None
@@ -1012,9 +1018,9 @@ class MachineManager(QObject):
 
         quality_changes_container = self._empty_quality_changes_container
         quality_container = self._empty_quality_changes_container
-        if quality_changes_group.node_for_global:
+        if quality_changes_group.node_for_global and quality_changes_group.node_for_global.getContainer():
             quality_changes_container = quality_changes_group.node_for_global.getContainer()
-        if quality_group.node_for_global:
+        if quality_group.node_for_global and quality_group.node_for_global.getContainer():
             quality_container = quality_group.node_for_global.getContainer()
 
         self._global_container_stack.quality = quality_container
@@ -1026,9 +1032,9 @@ class MachineManager(QObject):
 
             quality_changes_container = self._empty_quality_changes_container
             quality_container = self._empty_quality_container
-            if quality_changes_node:
+            if quality_changes_node and quality_changes_node.getContainer():
                 quality_changes_container = quality_changes_node.getContainer()
-            if quality_node:
+            if quality_node and quality_node.getContainer():
                 quality_container = quality_node.getContainer()
 
             extruder.quality = quality_container
@@ -1040,14 +1046,18 @@ class MachineManager(QObject):
         self.activeQualityChangesGroupChanged.emit()
 
     def _setVariantNode(self, position, container_node):
+        if container_node.getContainer() is None:
+            return
         self._global_container_stack.extruders[position].variant = container_node.getContainer()
         self.activeVariantChanged.emit()
 
     def _setGlobalVariant(self, container_node):
         self._global_container_stack.variant = container_node.getContainer()
+        if not self._global_container_stack.variant:
+            self._global_container_stack.variant = Application.getInstance().empty_variant_container
 
     def _setMaterial(self, position, container_node = None):
-        if container_node:
+        if container_node and container_node.getContainer():
             self._global_container_stack.extruders[position].material = container_node.getContainer()
             root_material_id = container_node.metadata["base_file"]
         else:

plugins/3MFReader/ThreeMFWorkspaceReader.py

@@ -895,7 +895,7 @@ class ThreeMFWorkspaceReader(WorkspaceReader):
             variant_type = VariantType.BUILD_PLATE
 
             node = variant_manager.getVariantNode(global_stack.definition.getId(), variant_name, variant_type)
-            if node is not None:
+            if node is not None and node.getContainer() is not None:
                 global_stack.variant = node.getContainer()
 
         for position, extruder_stack in extruder_stack_dict.items():
@@ -911,7 +911,7 @@ class ThreeMFWorkspaceReader(WorkspaceReader):
             variant_type = VariantType.NOZZLE
 
             node = variant_manager.getVariantNode(global_stack.definition.getId(), variant_name, variant_type)
-            if node is not None:
+            if node is not None and node.getContainer() is not None:
                 extruder_stack.variant = node.getContainer()
 
     def _applyMaterials(self, global_stack, extruder_stack_dict):
@@ -937,7 +937,7 @@ class ThreeMFWorkspaceReader(WorkspaceReader):
                                                              extruder_stack.variant.getName(),
                                                              machine_material_diameter,
                                                              root_material_id)
-            if material_node is not None:
+            if material_node is not None and material_node.getContainer() is not None:
                 extruder_stack.material = material_node.getContainer()
 
     def _applyChangesToMachine(self, global_stack, extruder_stack_dict):

plugins/XmlMaterialProfile/XmlMaterialProfile.py

@@ -71,11 +71,13 @@ class XmlMaterialProfile(InstanceContainer):
 
         # Update the root material container
         root_material_container = material_group.root_material_node.getContainer()
+        if root_material_container is not None:
             root_material_container.setMetaDataEntry(key, value, apply_to_all = False)
 
         # Update all containers derived from it
         for node in material_group.derived_material_node_list:
             container = node.getContainer()
+            if container is not None:
                 container.setMetaDataEntry(key, value, apply_to_all = False)
 
     ##  Overridden from InstanceContainer, similar to setMetaDataEntry.