Release 1.165.4

[odlbot]

annagav

• Skip duplicate learner records when transfering (Skip duplicate learner records when transfering #3942) (89623218)

James Kachel

• Update B2B provisioning; allow public course attachment (Update B2B provisioning; allow public course attachment #3903) (2dbdbfc2)

cp-at-mit

• Respect product-scoped discounts in pricing (Respect product-scoped discounts in pricing #3937) (f5af50dd)

Chris Chudzicki

• Cut per-order queries on GET /api/v0/orders/history/ from 17 to 10 (Cut per-order queries on GET /api/v0/orders/history/ from 17 to 10 #3934) (5cb6ebe4)

[github-actions]

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[sentry]

Bug: The ProductPurchasableObjectField.to_representation method does not handle None values, causing a crash when serializing an order line for a deleted product.
_{Severity: HIGH}

Suggested Fix

Add a null check at the beginning of the ProductPurchasableObjectField.to_representation() method. If the input value is None, the method should return None or an empty representation to prevent the InvalidPurchasableObjectTypeError exception.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location: ecommerce/serializers/__init__.py#L422

Potential issue: The `LineSerializer` was changed to use
`ProductSerializer(read_only=True)`. This serializer includes a `purchasable_object`
field handled by `ProductPurchasableObjectField`. If the underlying purchasable object
(e.g., a `CourseRun`) has been deleted from the database, the `GenericForeignKey` for it
will resolve to `None`. The `to_representation` method in
`ProductPurchasableObjectField` does not handle this `None` case. It fails all
`isinstance` checks and raises an `InvalidPurchasableObjectTypeError`. This will cause
API endpoints that serialize order history, such as `/api/v0/orders/history/`, to crash
for any user whose order contains a product associated with a deleted courseware item.

_{Did we get this right? 👍 / 👎 to inform future reviews.}