Error found while executing underground codes

[Aithal]

I was using the underground codes for Brilliant Diamond and only used the all button and tried saving and got the following error codes :

 

Exception Details:
System.NullReferenceException: Object reference not set to an instance of an object.
   at PKHeX.WinForms.SAV_Underground8b.SaveItems(IReadOnlyList`1 items)
   at PKHeX.WinForms.SAV_Underground8b.B_Save_Click(Object sender, EventArgs e)
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Loaded Assemblies:
--------------------
mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\mscorlib.dll

PKHeX, Version=21.11.27.0, Culture=neutral, PublicKeyToken=null
E:\Games\PKHeX BDSP\PKHeX.exe

System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System\v4.0_4.0.0.0__b77a5c561934e089\System.dll

System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Windows.Forms\v4.0_4.0.0.0__b77a5c561934e089\System.Windows.Forms.dll

System.Drawing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Drawing\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Drawing.dll

System.Configuration, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Configuration\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Configuration.dll

System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Core\v4.0_4.0.0.0__b77a5c561934e089\System.Core.dll

System.Xml, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Xml\v4.0_4.0.0.0__b77a5c561934e089\System.Xml.dll

PKHeX.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null

PKHeX.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null

System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51

System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Runtime\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Runtime.dll

System.Runtime.CompilerServices.Unsafe, Version=4.0.4.1, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a

System.Reflection, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Reflection\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Reflection.dll

System.Runtime.InteropServices, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.InteropServices\v4.0_4.0.0.0__b03f5f7f11d50a3a\System.Runtime.InteropServices.dll

Newtonsoft.Json, Version=13.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed

System.Numerics, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Numerics\v4.0_4.0.0.0__b77a5c561934e089\System.Numerics.dll

System.Runtime.Serialization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.Runtime.Serialization\v4.0_4.0.0.0__b77a5c561934e089\System.Runtime.Serialization.dll

System.Data, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089
C:\WINDOWS\Microsoft.Net\assembly\GAC_64\System.Data\v4.0_4.0.0.0__b77a5c561934e089\System.Data.dll

PKHeX.Drawing, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null

System.ValueTuple, Version=4.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51
C:\WINDOWS\Microsoft.Net\assembly\GAC_MSIL\System.ValueTuple\v4.0_4.0.0.0__cc7b13ffcd2ddd51\System.ValueTuple.dll

--------------------
User Message:
An unhandled exception has occurred.
You can continue running PKHeX, but please report this error.
 

[Kaphotics]

Unable to replicate on the latest builds.