How to reproduce:
1. Create a new project
2. Drag and drop into /Assets the custom package: “IN-112289_ModelBug.unitypackage”
3. When prompted to import the package, click “Import”
4. Observe the crash

Reproducible with: 6000.2.0a8 (8a36f491c000), 6000.2.0a9
Not reproducible with: 6000.0.57f1, 6000.2.0a7, 6000.2.3f1, 6000.3.0b1 (fcdf07aae9b4)
Fixed in: 6000.2.0a10

Reproducible on: Windows 11
Not reproducible on: No other environments tested

First few lines of the crash:
0x00007FFE4981FCA8 (Unity) SerializedFile::IndexTextFile
0x00007FFE4982102D (Unity) SerializedFile::InitializeRead
0x00007FFE49805210 (Unity) PersistentManager::GetStreamNameSpaceInternal
0x00007FFE49803479 (Unity) PersistentManager::GetAllFileIDs
0x00007FFE49803DB0 (Unity) PersistentManager::GetInstanceIDsAtPath