fix: guard MigrateFrom1To2 against DirectoryNotFoundException on init

[kaan-barmore-genc-mixpanel]

Summary

Fixes SDK-133. Customers hit a recurring init failure in the Unity SDK: Mixpanel fallback initialization failed: System.IO.DirectoryNotFoundException ... /mp_state.json.

Root cause

MigrateFrom1To2() in Controller.cs deleted legacy v1 files (mp_state.json, mp_super_properties.json) with File.Delete inside finally blocks — no File.Exists guard, and outside the protecting catch. File.Delete only tolerates a missing file when the parent directory exists, so when Application.persistentDataPath is empty or its directory is unavailable, the delete throws DirectoryNotFoundException. Running in finally meant the surrounding catch did not swallow it, so the exception escaped Initialize(), left _fullyInitialized == false, and Start() took the fallback path and logged the customer-visible failure.

persistentDataPath can be empty when read off the Unity main thread, on tvOS, or with a malformed ProductName/CompanyName.

Fix

• Route both deletes through a DeleteLegacyFileBestEffort helper that guards File.Exists and swallows exceptions — legacy cleanup is best-effort and must never abort init.
• Skip migration cleanly when persistentDataPath is empty, without marking migration done, so a later init can still run it.

Testing

No automated coverage — the repo has a single EditMode test (Identify_Test) and CI does not run it (Unity license required). Nothing exercises the migration path. Verified by inspection of the throw semantics.

[linear-code]

SDK-133

[greptile-apps]

Confidence Score: 3/5

The retry behavior should be fixed before merging because a transiently empty storage path can permanently skip migration of identity and consent state.

The new early return preserves the migration flag but both callers subsequently set _fullyInitialized, preventing normal later initialization attempts from retrying the migration.

Files Needing Attention: Mixpanel/Controller.cs

Important Files Changed

Filename	Overview
Mixpanel/Controller.cs	Safely handles legacy-file cleanup, but an empty-path skip is not retried after initialization becomes complete.

_{Reviews (1): Last reviewed commit: "fix: guard MigrateFrom1To2 against Direc..." | Re-trigger Greptile}