MapProperty with nullable reference types broken for IQueryable projections in v3.6.0

[lschloetterer]

Describe the bug
The MapProperty Attribute does not generate the appropriate code anymore for projections in the latest version.
This behaviour applies when Nullable types are not enabled in the csproj file.
It works up until v3.5.1 (see actual vs expected code below)

Declaration code

public class Car
{
  public int Id { get; set; }
  public string Manufacturer { get; set; }
}

public class CarDto
{
  public int Id { get; set; }
  public string Producer { get; set; }
}

[Mapper]
public static partial class CarMapper
{
  public static partial IQueryable<CarDto> ProjectToDto(this IQueryable<Car> q);

  [MapProperty(nameof(Car.Manufacturer), nameof(CarDto.Producer))]
  private static partial CarDto Map(Car car);
}

Actual relevant generated code

    public static partial class CarMapper
    {
        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "3.6.0.0")]
        public static partial global::System.Linq.IQueryable<global::MapperlyIQueryableBug.CarDto?>? ProjectToDto(this global::System.Linq.IQueryable<global::MapperlyIQueryableBug.Car?>? q)
        {
            if (q == null)
                return default;
#nullable disable
            return System.Linq.Queryable.Select(q, x => new global::MapperlyIQueryableBug.CarDto()
            {
                Id = x.Id,
            });
#nullable enable
        }

        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "3.6.0.0")]
        private static partial global::MapperlyIQueryableBug.CarDto? Map(global::MapperlyIQueryableBug.Car? car)
        {
            if (car == null)
                return default;
            var target = new global::MapperlyIQueryableBug.CarDto();
            target.Id = car.Id;
            target.Producer = car.Manufacturer;
            return target;
        }
    }

Expected relevant generated code

    public static partial class CarMapper
    {
        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "3.5.1.0")]
        public static partial global::System.Linq.IQueryable<global::MapperlyIQueryableBug.CarDto?>? ProjectToDto(this global::System.Linq.IQueryable<global::MapperlyIQueryableBug.Car?>? q)
        {
            if (q == null)
                return default;
#nullable disable
            return System.Linq.Queryable.Select(q, x => x == null ? default : new global::MapperlyIQueryableBug.CarDto()
            {
                Id = x.Id,
                Producer = x.Manufacturer,
            });
#nullable enable
        }

        [global::System.CodeDom.Compiler.GeneratedCode("Riok.Mapperly", "3.5.1.0")]
        private static partial global::MapperlyIQueryableBug.CarDto? Map(global::MapperlyIQueryableBug.Car? car)
        {
            if (car == null)
                return default;
            var target = new global::MapperlyIQueryableBug.CarDto();
            target.Id = car.Id;
            target.Producer = car.Manufacturer;
            return target;
        }
    }

Environment (please complete the following information):

• Mapperly Version: v3.6.0, also same behaviour in v4.0.0-next.4
• Nullable reference types: disabled
• .NET Version: .NET 8.0.202
• Target Framework: .net8.0
• Compiler Version: 4.9.0-3.24121.1 (a98c90d5)
• C# Language Version: 12.0
• IDE: Visual Studio v17.9.4
• OS: Windows 11

Additional context

[Dazfl]

We have exactly the same issue. It is preventing us from upgrading from 3.5.1 to the latest.

[latonz]

This seems to be a regression of #1196.
4.1.1-next.0 should include a fix for this bug, feel free to give it a try and provide feedback.

[Dazfl]

Just tested the fix in 4.1.1-next.0, and it appears to be working as intended.