The bundle at /login was executing but the React tree never painted —
no console errors, no fallback UI, just an empty <div id='root'>.
Add three layers of defense so a future failure of this shape is
captured instead of being silently swallowed:
1. window 'error' and 'unhandledrejection' listeners in main.tsx,
printing structured context to console.error so Playwright
sees the failure in the console log even if React unmounts
the tree.
2. A top-level <ErrorBoundary> in main.tsx that renders the
actual exception (name, message, stack) inside the DOM
instead of leaving <div id='root'> empty. The boundary also
logs to console.error via componentDidCatch.
3. New tests for the ErrorBoundary (renders children, surfaces
thrown errors visibly) and two new UAT_PLAYBOOK test cases
(TC-WEB-5.1.6 / 5.1.7) that explicitly assert the
'never-blank-root' invariant on UAT.
Co-Authored-By: Paperclip <noreply@paperclip.ing>
Flea Flicker