Unable to spread fragment on inheritance hierarchy added as a union or interface type when deferred to Entity Framework.

[TeunKooijman]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Given an inheritance hierarchy, added to the schema as either a union type or interface type, and resolvers that defer directly to an IQueryable in the form of a DbSet from Entity Framework, issueing a query that spreads a fragment on a specific concrete subtype in the hierarchy, yields an execution exception, unless a field on the base type is projected.

Steps to reproduce

Please see the reproduction repository at https://github.com/TeunKooijman/reproductions-hotchocolate

Relevant log output

No response

Additional Context?

Please see the README.md in the reproduction repository at https://github.com/TeunKooijman/reproductions-hotchocolate

Product

Hot Chocolate

Version

12.0.1

[msawczyn]

Additional information: I ran through the repro listed above and noticed that, if you remove the [UseProjection] attribute, the problem doesn't surface. I surmise that this is because, without [UseProjection], HC allows Entity Framework to bring the full object into the context, with the correct type, rather than creating an anonymous type.