CURA-4839 Create variable before asignment

plugins/3MFReader/ThreeMFWorkspaceReader.py

@@ -704,6 +704,8 @@ class ThreeMFWorkspaceReader(WorkspaceReader):
 
         # load extruder stack files
         has_extruder_stack_files = len(extruder_stack_files) > 0
+        empty_quality_container = self._container_registry.findInstanceContainers(id = "empty_quality")[0]
+        empty_quality_changes_container = self._container_registry.findInstanceContainers(id = "empty_quality_changes")[0]
         try:
             for extruder_stack_file in extruder_stack_files:
                 container_id = self._stripFileToId(extruder_stack_file)
@@ -779,7 +781,6 @@ class ThreeMFWorkspaceReader(WorkspaceReader):
                 self._container_registry.removeContainer(container.getId())
             return
 
-
         # Check quality profiles to make sure that if one stack has the "not supported" quality profile,
         # all others should have the same.
         #
@@ -811,17 +812,12 @@ class ThreeMFWorkspaceReader(WorkspaceReader):
         quality_has_been_changed = False
 
         if has_not_supported:
-            empty_quality_container = self._container_registry.findInstanceContainers(id = "empty_quality")[0]
             for stack in [global_stack] + extruder_stacks_in_use:
                 stack.replaceContainer(_ContainerIndexes.Quality, empty_quality_container)
-            empty_quality_changes_container = self._container_registry.findInstanceContainers(id = "empty_quality_changes")[0]
-            for stack in [global_stack] + extruder_stacks_in_use:
                 stack.replaceContainer(_ContainerIndexes.QualityChanges, empty_quality_changes_container)
             quality_has_been_changed = True
 
         else:
-            empty_quality_changes_container = self._container_registry.findInstanceContainers(id="empty_quality_changes")[0]
-
             # The machine in the project has non-empty quality and there are usable qualities for this machine.
             # We need to check if the current quality_type is still usable for this machine, if not, then the quality
             # will be reset to the "preferred quality" if present, otherwise "normal".