Please tell me this mesh is salvageable

How bad is it? Be honest



I tried to edit the beak from LilyValley's furry set to make a custom head for an OC (a project way beyond my skill level in hindsight). First, when I imported the edited mesh into the cloned package, I got this error:

The Sims 4 Studio - Version 3.2.2.1
System.NullReferenceException: Object reference not set to an instance of an object.
at S4Studio.Data.IO.CAS.Geometry.VertexDeclaration.WriteData(Stream stream, Single[] data) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\CAS\Geometry\VertexDeclaration.cs:line 147
at S4Studio.Data.IO.CAS.GeometryResource.WriteData(Stream stream, IReferenceList serializer) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\CAS\Geometry\GeometryResource.cs:line 598
at S4Studio.Data.IO.Core.LinkedResourceSerializer.Write(Stream stream) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\Core\LinkedResourceSerializer.cs:line 398
at S4Studio.Data.IO.Core.LinkedResource.Write(Stream stream) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\Core\LinkedResource.cs:line 117
at S4Studio.Data.IO.Package.DBPFPackage.WriteResourceStream(FileStream final_stream, IPackedResource resource, IDBPFResourcePointer index) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\Package\DBPFPackage.cs:line 555
at S4Studio.Data.IO.Package.DBPFPackage.WriteDataStream(Stream src_stream, FileStream final_stream) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\Package\DBPFPackage.cs:line 524
at S4Studio.Data.IO.Package.DBPFPackage.SaveTempPackage(String out_file, String tmp, Stream pkg_stream) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\Package\DBPFPackage.cs:line 459
at S4Studio.Data.IO.Package.DBPFPackage.Save(String out_file, Boolean inline, String temp_path) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\IO\Package\DBPFPackage.cs:line 375
at S4Studio.Shared.StudioDocumentModel.Save(String filename) in \\mac\thes4studio\TheS4Studio\S4Studio.Shared\ViewModels\App\StudioDocumentModel.cs:line 357

but when I used a package cloned from an EA hat, it saved with no error. Mesh appears ok in s4s:



Then I tested it in-game, and witnessed that lovely piece of abstract art shown earlier.

I'm worried that the geometry might be screwed beyond salvation, or that I might've messed up the vertex group weights.

Here's the link to the blend file and package:link

Please ignore the hat textures and lods; I will get there when/if I get there.