Steps to reproduce:
1. Open the “new user’s attached project”
2. Observe the crash

Alternatively:
1. Open the “user’s attached project”
2. Open the “Main” Scene
3. Make small changes in the Scene
4. Close the Editor
5. Open the Editor again
6. If no crash occurs, repeat steps 2-5
7. Observe crash

Reproducible with versions: 6000.4.0a2 (tested by the user), 6000.5.0a5 (tested by CQA)
Not reproducible with versions: 6000.0.66f1, 6000.3.7f1 (tested by the user)

Reproducible on: Windows 11, macOS 15.7.3 (M1 Max)
Not reproducible on: no other environment tested

Notes:
- Reproduced by CQA only on 6000.5.0a5 with the “new user’s attached project”
- The crash is very inconsistent, so downgrading the “new user’s attached project” to any version results in no reproduction

First few lines of StackTrace:
0x00007FFEFE93C600 (Unity) core::basic_string<char,core::StringStorageDefault<char> >::find
0x00007FFEFE9A6268 (Unity) core::basic_string<char,core::StringStorageDefault<char> >::find
0x00007FFF01604841 (Unity) keywords::LocalSpace::StateFromKeywordNames
0x00007FFF0161CEBA (Unity) ShaderVariantCollection::WarmupOneShaderImpl
0x00007FFF0161D8F9 (Unity) ShaderVariantCollection::WarmupShadersImpl