Pk3ds Breaks when I edit trainer battles?

[YouOne_]

I've been making a totally custom hack of Alpha Sapphire and i'm at the postgame now and when I try and edit the battles for some trainers names Grunt - 207, it gives me this error message and if I load the game while its active it just freezes.
I'm playing the game using Citra Nightly 2043 but it breaks before I even get into the emulator. Anyone know how I can fix this? I'm sure it would work if I just went back to one of my backups but that would mean I'd need to remake a bunch of battles and that would take ages, plus I don't want to have to do that every time this might happen again.

Here's the error I get, any advice would be great.

 

Exception Details:
System.ArgumentOutOfRangeException: InvalidArgument=Value of '65535' is not valid for 'SelectedIndex'.
Parameter name: SelectedIndex
   at System.Windows.Forms.ComboBox.set_SelectedIndex(Int32 value)
   at pk3DS.RSTE.ReadFile() in D:\a\1\s\pk3DS\Subforms\Gen6\RSTE.cs:line 271
   at System.Windows.Forms.ComboBox.OnSelectedIndexChanged(EventArgs e)
   at System.Windows.Forms.ComboBox.WmReflectCommand(Message& m)
   at System.Windows.Forms.ComboBox.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

pk3DS, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
C:\Users\hammy\OneDrive\Desktop\pk3DS\pk3DS.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.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.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.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

pk3DS.Core, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
C:\Users\hammy\OneDrive\Desktop\pk3DS\pk3DS.Core.dll

--------------------
User Message:
An unhandled exception has occurred.
You can continue running the program (albeit with potential side-effects), but please report this error.