Null Reference Exception when attempting to query entity with Owned List

[dave-hillier]

This seems very closely related to:

#15600

To reproduce follow the steps in the previous bug, except add the line: await context.Distributors.ToArrayAsync();

You don't need to add the items even empty DB causes this exception.

This throws the exception:

System.NullReferenceException : Object reference not set to an instance of an object.
  Stack Trace:
     at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryQueryExpression.<>c.<ApplyServerProjection>b__18_0(Expression e)
   at System.Linq.Enumerable.SelectListIterator`2.ToArray()
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryQueryExpression.ApplyServerProjection()
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryShapedQueryCompilingExpressionVisitor.VisitShapedQueryExpression(ShapedQueryExpression shapedQueryExpression)
   at Microsoft.EntityFrameworkCore.Query.ShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at Microsoft.EntityFrameworkCore.InMemory.Query.Internal.InMemoryShapedQueryCompilingExpressionVisitor.VisitExtension(Expression extensionExpression)
   at System.Linq.Expressions.Expression.Accept(ExpressionVisitor visitor)
   at System.Linq.Expressions.ExpressionVisitor.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.QueryCompilationContext.CreateQueryExecutor[TResult](Expression query)
   at Microsoft.EntityFrameworkCore.Storage.Database.CompileQuery[TResult](Expression query, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](IDatabase database, Expression query, IModel model, Boolean async)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass12_0`1.<ExecuteAsync>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQuery[TResult](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.ExecuteAsync[TResult](Expression query, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryProvider.ExecuteAsync[TResult](Expression expression, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.EntityQueryable`1.GetAsyncEnumerator(CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.System.Collections.Generic.IAsyncEnumerable<TEntity>.GetAsyncEnumerator(CancellationToken cancellationToken)
   at System.Runtime.CompilerServices.ConfiguredCancelableAsyncEnumerable`1.GetAsyncEnumerator()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToArrayAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)

Full repro, with entities that are snipped from the documentation

using System.Collections.Generic;
using Microsoft.EntityFrameworkCore;
using Xunit;

namespace repro
{
    [Owned]
    public class StreetAddress
    {
        public string Street { get; set; }
        public string City { get; set; }
    }

    public class Distributor
    {
        public int Id { get; set; }
        public ICollection<StreetAddress> ShippingCenters { get; set; }
    }

    public class ApplicationDbContext : DbContext
    {
        public DbSet<Distributor> Distributors { get; set; }
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
        {

        }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Distributor>().OwnsMany(p => p.ShippingCenters, a =>
            {
                a.WithOwner().HasForeignKey("OwnerId");
                a.Property<int>("Id");
                a.HasKey("Id");
            });
        }
    }
    public class UnitTest1
    {
        [Fact]
        public async void Test1()
        {
            var optionsBuilder = new DbContextOptionsBuilder<ApplicationDbContext>();
            optionsBuilder.UseInMemoryDatabase("x");
            using (var context = new ApplicationDbContext(optionsBuilder.Options))
            {
                var y = await context.Distributors.ToArrayAsync();
            }
        }
    }
}

Further technical details

EF Core version: 3.0 Preview 9
Database provider: InMemory
Target framework: 3.0 Preview 9
Operating system: MacOS

[smitpatel]

Probably duplicate of #16963 and fixed in 3.0 rc1 release.

[dave-hillier]

I tried 3.0.0-rc1.19456.14 seems to be fixed.

Though there seems to be yet more breaking changes, the main project I'm using is saying I have duplicate keys now that weren't there before... upgrading across 2.2 to 3 has been a real challenge! This is just a hobby project, I wonder if anyone is actually using this functionality?