Return empty model if there is no printer added yet

Contributes to issue CURA-6597.

cura/Machines/Models/IntentModel.py

@@ -48,6 +48,8 @@ class IntentModel(ListModel):
         application = cura.CuraApplication.CuraApplication.getInstance()
         quality_manager = application.getQualityManager()
         global_stack = application.getGlobalContainerStack()
+        if not global_stack:
+            self.setItems(new_items)
 
         for intent_category, quality_type in IntentManager.getInstance().currentAvailableIntents():
             if intent_category == self._intent_category: