Query: Group by on Join without DefaultIfEmpty throws ArgumentException

[mikary]

Similar to #3316, an ArgumentException is thrown when compiling the following query:

[ConditionalFact]
public virtual void GroupBy_join_anonymous()
{
    AssertQuery<Order, OrderDetail>((os, ods) =>
        (from order in os
            join orderDetail in ods on order.OrderID equals orderDetail.OrderID into orderJoin
            from orderDetail in orderJoin
            group new
            {
                orderDetail.ProductID,
                orderDetail.Quantity,
                orderDetail.UnitPrice
            } by new
            {
                order.OrderID,
                order.OrderDate
            })
            .Where(x => x.Key.OrderID == 10248),
        asserter: (l2oResults, efResults) =>
        {
            var l2oGroup = l2oResults.Cast<IGrouping<dynamic, dynamic>>().Single();
            var efGroup = efResults.Cast<IGrouping<dynamic, dynamic>>().Single();

            Assert.Equal(l2oGroup.Key, efGroup.Key);

            Assert.Equal(
                l2oGroup.OrderBy(element => element.ProductID),
                efGroup.OrderBy(element => element.ProductID));
        });
}

Exception details:

System.ArgumentException occurred
  HResult=-2147024809
  Message=Argument type 'System.Collections.Generic.IEnumerable`1[Microsoft.EntityFrameworkCore.Storage.ValueBuffer]' does not match the corresponding member type 'System.Collections.Generic.IEnumerable`1[Microsoft.EntityFrameworkCore.Specification.Tests.TestModels.Northwind.OrderDetail]'
  Source=System.Core
  StackTrace:
       at System.Linq.Expressions.Expression.ValidateNewArgs(ConstructorInfo constructor, ReadOnlyCollection`1& arguments, ReadOnlyCollection`1& members)
  InnerException: 

[maumar]

This issue is now fixed, regression test added here: f274b88