Cannot load aggregate if the loaded relationship loads another relationship

[sezaru]

Describe the bug
If the aggregated resource has a default preparation that will load other resources, the aggregation will fail

To Reproduce
First we have a resource with these aggregations and relationships:

  aggregates do
    count :total_students, :students
    count :total_classes, :classes
  end

  relationships do
    alias Core.Feedbacks

    has_many :classes, Feedbacks.Class
    has_many :students, Feedbacks.Student
  end

And in the Class resource, we have the following preparations:

  preparations do
    prepare build(load: [:students])
  end

Now, if we try to load :total_classes we will get the following error:

iex(18)> Core.Feedbacks.read!(Core.Feedbacks.School) |> List.first |> Core.Feedbacks.load([:total_classes])
[debug] QUERY OK source="schools" db=0.3ms idle=795.8ms
SELECT s0."id", s0."name", s0."inserted_at", s0."updated_at", s0."organization_id" FROM "schools" AS s0 []
{:error,
 %Ash.Error.Unknown{
   errors: [
     %Ash.Error.Unknown.UnknownError{
       error: "Cannot load in an aggregate.",
       field: nil,
       changeset: nil,
       query: nil,
       error_context: ["Loading aggregate: :total_classes for query: #Ash.Query<resource: Core.Feedbacks.School>"],
       vars: [],
       path: [:aggregates],
       stacktrace: #Stacktrace<>,
       class: :unknown
     }
   ],
   stacktraces?: true,
   changeset: nil,
   query: nil,
   error_context: [],
   vars: [],
   path: [],
   stacktrace: #Stacktrace<>,
   class: :unknown
 }}

Expected behavior
The aggregation should work and the preparations of the other resource should be ignored.

Runtime

• Elixir version 1.15
• Erlang version 26
• OS Fedora 39
• Ash version 2.17.13