Visual Studio assumes return value from FirstOrDefaultAsync() cannot be null

[SoftCircuits]

I have the following query.

var railcarInfo = await (from rt in DbContext.RailcarTrips
                         where rt.WaybillRailcar.RailcarNumber == clm.RailcarNumber &&
                         rt.WaybillRailcar.Waybill.CreateDate <= clm.SightingDate
                         orderby rt.WaybillRailcar.Waybill.CreateDate descending
                         select new
                         {
                             RailcarTrip = rt,
                             WaybillCreateDate = rt.WaybillRailcar.Waybill.CreateDate,
                             IsLoaded = rt.WaybillRailcar.Weight > 0
                         })
                         .AsNoTracking()
                         .FirstOrDefaultAsync();

But for some reason, Visual Studio decides that 'railcarInfo' is not null here immediately following this query.

The point of FirstOrDefaultAsync() is that it returns the first item in a collection, or null if the collection is empty. It could definitely be null here. Seems Visual Studio got confused?

Include provider and version information

Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET 5.0
Operating system: Windows 11
IDE: Visual Studio 2019 16.11.5

[roji]

Duplicate of #19007

[roji]

@SoftCircuits the FirstOrDefaultAsync operator is part of EF Core, and EF Core wasn't annotated for nullable reference types. Try EF Core 6.0 RC2, it should work there.