Unable to cast UndertaleGeneralInfo to UndertaleExtensionFile

[iconmaster5326]

Describe the bug

When I attempt to open up the data.win file for the game Siralim Ultimate, I get the following error:

An error occured while trying to load: Unable to cast object of type 'UndertaleModLib.Models.UndertaleGeneralInfo' to type 'UndertaleModLib.Models.UndertaleExtensionFile'.

at 00000718 while reading object UndertaleModLib.UndertalePointerList'1 [[UndertaleModLib.Mo dels.UndertaleExtensionFile, UndertaleModLib, Version=0.4.0.4, Culture=neutral, PublicKeyToken=null]]
at 00000718 while reading object UndertaleModLib.Models.UndertaleExtension while reading item 1 of 3 in a list of UndertaleModLib.Models.UndertaleExtension in chunk EXTN 

Reproducing steps

1. Open Siralim Ultimate's data.win file in the tool.
2. You now see the above error message.

Setup Details

1. 0.4.0.4
2. Windows 10
3. Siralim Ultimate