Opening a window whose target was removed from the registry (its tab
stays open by design) and failing landed in the action menu with a
"重试连接" row that indexed self.entries directly and raised KeyError,
killing the popup with a traceback.
Only offer the retry action for registered targets, degrade a stale
retry row to a message, and keep the popup alive when a handler raises
anything unexpected instead of dying with a traceback.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>