Debugger disagrees with Debug.Assert

One of my constructors was throwing a "ArgumentNullException", so I start debugging.

And I found this weird issue. As you can see, the debugger says my propsSegment is NOT null; yet the Debug.Assert says it IS null.

What is going on here?

This is a .Net Core 2.0 project, being compiled to x64. I'm running a single thread and have plenty of memory to spare.

If you guys want to check the source, the project is hosted here. I created a branch just to show this issue. If you try to compile it, you'll need a "otbm" file. The one I'm using is zipped here

Edit: the downvotes makes me think I'm missing something obvious. Could someone please just tell me what is it?

And the full stack trace:

System.ArgumentNullException
  HResult=0x80004003
  Message=Value cannot be null.
  Source=System.Private.CoreLib
  StackTrace:
   at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.ArraySegment`1.op_Implicit(T[] array)
   at COTS.GameServer.World.WorldLoader.ConvertingParsingNode(Byte[] serializedWorldData, ParsingWorldNode subtree) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 153
   at COTS.GameServer.World.WorldLoader.<>c__DisplayClass10_0.<ConvertingParsingNode>b__0(ParsingWorldNode c) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 148
   at System.Linq.Enumerable.SelectListIterator`2.ToArray()
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at COTS.GameServer.World.WorldLoader.ConvertingParsingNode(Byte[] serializedWorldData, ParsingWorldNode subtree) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 146
   at COTS.GameServer.World.WorldLoader.<>c__DisplayClass10_0.<ConvertingParsingNode>b__0(ParsingWorldNode c) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 148
   at System.Linq.Enumerable.SelectListIterator`2.ToArray()
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at COTS.GameServer.World.WorldLoader.ConvertingParsingNode(Byte[] serializedWorldData, ParsingWorldNode subtree) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 146
   at COTS.GameServer.World.WorldLoader.<>c__DisplayClass10_0.<ConvertingParsingNode>b__0(ParsingWorldNode c) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 148
   at System.Linq.Enumerable.SelectListIterator`2.ToArray()
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at COTS.GameServer.World.WorldLoader.ConvertingParsingNode(Byte[] serializedWorldData, ParsingWorldNode subtree) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 146
   at COTS.GameServer.World.WorldLoader.<>c__DisplayClass10_0.<ConvertingParsingNode>b__0(ParsingWorldNode c) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 148
   at System.Linq.Enumerable.SelectListIterator`2.ToArray()
   at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
   at COTS.GameServer.World.WorldLoader.ConvertingParsingNode(Byte[] serializedWorldData, ParsingWorldNode subtree) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 146
   at COTS.GameServer.World.WorldLoader.ConvertParsingTree(Byte[] serializedWorldData, ParsingWorldNode root) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 135
   at COTS.GameServer.World.WorldLoader.ParseWorld(Byte[] serializedWorldData) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\World\WorldLoader.Methods.cs:line 31
   at COTS.GameServer.Program.Main(String[] args) in C:\Source\CoreOpenTibiaServer\CoreOpenTibiaServer\src\COTS.GameServer\Program.cs:line 20

This is an open issue with ArraySegment. See https://github.com/dotnet/coreclr/issues/14012

Note though, that you do not need to check for null since ArraySegment is a struct.

My guess is that the equality operator for ArraySegment is trying to implicitly convert the null to an ArraySegment, and that may be what is generating the actual NullReference exception.