[bug] Fix post-delete actions (#12575)

- Check that underlying part is still available

src/backend/InvenTree/company/models.py

@@ -1044,15 +1044,27 @@ class SupplierPriceBreak(common.models.PriceBreak):
 )
 def after_save_supplier_price(sender, instance, created, **kwargs):
     """Callback function when a SupplierPriceBreak is created or updated."""
-    if (
-        (
-            InvenTree.ready.canAppAccessDatabase(allow_test=settings.TESTING_PRICING)
-            and not InvenTree.ready.isImportingData()
-        )
-        and instance.part
-        and instance.part.part
-    ):
-        instance.part.part.schedule_pricing_update(create=True)
+    from part.models import Part
+
+    if not InvenTree.ready.canAppAccessDatabase(allow_test=settings.TESTING_PRICING):
+        return
+
+    if InvenTree.ready.isImportingData():
+        return
+
+    try:
+        supplier_part = instance.part
+    except SupplierPart.DoesNotExist:
+        # The underlying SupplierPart instance has been deleted
+        return
+
+    try:
+        base_part = supplier_part.part
+    except Part.DoesNotExist:
+        # The underlying Part instance has been deleted
+        return
+
+    base_part.schedule_pricing_update(create=True)
 
 
 @receiver(
@@ -1062,12 +1074,24 @@ def after_save_supplier_price(sender, instance, created, **kwargs):
 )
 def after_delete_supplier_price(sender, instance, **kwargs):
     """Callback function when a SupplierPriceBreak is deleted."""
-    if (
-        (
-            InvenTree.ready.canAppAccessDatabase(allow_test=settings.TESTING_PRICING)
-            and not InvenTree.ready.isImportingData()
-        )
-        and instance.part
-        and instance.part.part
-    ):
-        instance.part.part.schedule_pricing_update(create=False)
+    from part.models import Part
+
+    if not InvenTree.ready.canAppAccessDatabase(allow_test=settings.TESTING_PRICING):
+        return
+
+    if InvenTree.ready.isImportingData():
+        return
+
+    try:
+        supplier_part = instance.part
+    except SupplierPart.DoesNotExist:
+        # The underlying SupplierPart instance has been deleted
+        return
+
+    try:
+        base_part = supplier_part.part
+    except Part.DoesNotExist:
+        # The underlying Part instance has been deleted
+        return
+
+    base_part.schedule_pricing_update(create=False)

src/backend/InvenTree/stock/models.py

@@ -3593,23 +3593,32 @@ class StockItem(
 def after_delete_stock_item(sender, instance: StockItem, **kwargs):
     """Function to be executed after a StockItem object is deleted."""
     from part import tasks as part_tasks
+    from part.models import Part
 
     if InvenTree.ready.isImportingData():
         return
 
+    try:
+        base_part = instance.part
+    except Part.DoesNotExist:
+        return
+
+    if not base_part:
+        # Base part does not exist, or has been deleted
+        return
+
     if InvenTree.ready.canAppAccessDatabase(allow_test=True):
         # Run this check in the background
         InvenTree.tasks.offload_task(
             part_tasks.notify_low_stock_if_required,
-            instance.part.pk,
+            base_part.pk,
             group='notification',
             force_async=True,
         )
 
     if InvenTree.ready.canAppAccessDatabase(allow_test=settings.TESTING_PRICING):
         # Schedule an update on parent part pricing
-        if instance.part:
-            instance.part.schedule_pricing_update(create=False)
+        base_part.schedule_pricing_update(create=False)
 
 
 @receiver(post_save, sender=StockItem, dispatch_uid='stock_item_post_save_log')