EF 6 .0 GroupBy select Top N Query Count() Throw Exception

[ByZhouhang]

Include your code

I see in the documentation that ef6.0 support for GroupBy queries
https://docs.microsoft.com/en-us/ef/core/what-is-new/ef-core-6.0/whatsnew#improved-groupby-support

I have a paginated list (grouped to take the first N items), and when I try query.Count(), it throws an exception and does not query the database

var query= context.People
    .Include(e => e.Shoes)
    .GroupBy(e => e.Id)
    .Select(g => { PeopleId=g.key,   Count=g.Shoes.Count(),Top2List=   g.Shoes.take(2)});


var count=query.Count()  //Throw  exception  Nullable object must have a value.
var list =query.ToList()  // can be queried
var list2=query.Skip(0).Take(10).ToList() // can be queried

[smitpatel]

Duplicate of #27796