Reproduction steps:
1. Create a new project with any template or open an existing project
2. Observe the Editor crash or “{{error CS0006: Metadata file could not be found"}} errors in the console (if the Editor opens) and a crash after

Reproducible with versions: 2022.3.20f1 (2.6.0), 2022.3.8f1 (2.7.1)

Reproducible on: macOS, Windows 10, Windows 11
Not reproducible on: No other environment tested

Workaround:
- Deleting the library folder or a clean reinstall of the Editor fixes the issue

Notes:
- CQA could not reproduce the issue locally
- The “{{Library/PackageCache/com.unity.collab-proxy@2.7.1/Lib/Editor/PlasticSCM}}" folder is missing, and the missing files mentioned in the error are located in the “{{Library/PackageCache/com.unity.collab-proxy@2.7.1/Lib/Editor}}" folder

First few lines of StackTrace:

{noformat}#0 0x000001691deb48 in mono_custom_attrs_from_class_checked
#1 0x000001691deb10 in mono_custom_attrs_from_class
#2 0x00000101b0ce94 in scripting_class_has_attribute(ScriptingClassPtr, ScriptingClassPtr)
#3 0x00000101bbd8ac in PersistentManager::IsObjectNonTextSerialized(Object)
#4 0x00000101bbae64 in PersistentManager::WriteFile(core::basic_string_ref<char>, int, WriteData const, int, GlobalBuildData const&, VerifyWriteObjectResult ()(Object, BuildTargetSelection), BuildTargetSelection, TransferInstructionFlags, WriteInformation&, InstanceIDResolver const, PersistentManager::LockFlags, int ()(PersistentManager::ReportWriteObjectStep, int, core::basic_string<char, core::StringStorageDefault<char>> const&, int, void), void){noformat}