Symfony's logout responds with a redirect, causing fetch to parse HTML
as JSON and reject — .finally() ensures the UI always transitions.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Symfony 8 SPA with Doctrine ORM, Symfony Security, vanilla JS frontend.
Migrated from plain PHP (delight-im/auth + raw SQL) to full Symfony stack.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>