end
Ends the active onboarding session, restoring normal pk_/sk_ authentication.
Parameters
client
When non-null, the token is cleared only if it still matches this value. This makes teardown safe against out-of-order disposals: a stale onboarding view tearing down after a newer one has already begun its own session will not wipe the newer token. Pass the same value given to beginOnboardingSession. A null argument clears unconditionally (legacy behavior).