Value cannot be null. Parameter name: key

[InSimpleTermsJordan]

When running (in Powershell) .\PD2SE.exe -i .\save098.sav -o output.sav (with both PD2SE.exe and save098.sav (freshly copied from %localappdata%\PAYDAY 2\saves\<steamid>\), the following text is produced:

An unknown error has occured: Value cannot be null.
Parameter name: key

Interestingly enough, I encounter this same error when attempting to launch PayDay2SaveView (which I finally figured out how to build properly after an hour or two (there's absolutely no documentation about it on its repo, and it doesn't accept issue submissions)). Its text is more verbose though:

Unhandled Exception: System.ArgumentNullException: Value cannot be null.
Parameter name: key
   at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at PaydaySaveEditor.PD2.GameData.ReadDictionary(BinaryReader br) in C:\Users\JKPwnage\noSync\PayDay2SaveView\PaydaySaveEditor\PD2\GameData.cs:line 115
   at PaydaySaveEditor.PD2.GameData.ReadDictionary(BinaryReader br) in C:\Users\JKPwnage\noSync\PayDay2SaveView\PaydaySaveEditor\PD2\GameData.cs:line 118
   at PaydaySaveEditor.PD2.GameData.ReadDictionary(BinaryReader br) in C:\Users\JKPwnage\noSync\PayDay2SaveView\PaydaySaveEditor\PD2\GameData.cs:line 118
   at PaydaySaveEditor.PD2.GameDataBlock..ctor(BinaryReader br) in C:\Users\JKPwnage\noSync\PayDay2SaveView\PaydaySaveEditor\PD2\GameDataBlock.cs:line 18
   at PaydaySaveEditor.PD2.SaveFile..ctor(String filePath, Boolean encrypted) in C:\Users\JKPwnage\noSync\PayDay2SaveView\PaydaySaveEditor\PD2\SaveFile.cs:line 68
   at PayDay2SaveView.Program.Main(String[] args) in C:\Users\JKPwnage\noSync\PayDay2SaveView\PayDay2SaveView\Program.cs:line 22

I know it's been nearly a decade since this was made, but hopefully you can give some guidance.