add test for throw PersistDirError in `persist.spec.ts`

[BioPhoton]

💡 🧩 core: TODO: should throw PersistDirError
https://github.com/flowup/quality-metrics-cli/blob/317167e955a56bfe8579192d6463bfeab585037e/packages/core/src/lib/implementation/persist.spec.ts#L169

[BioPhoton]

closed in favour of #356