Previously the 404/500 React ErrorPage set the page content but not
document.title, so the browser tab showed the URL path instead of
a localized title. Added <title> element + imperative document.title
assignment (pattern from SeoHead.tsx) so both SSR and client set
the tab title to "<code> — <localized-title>", e.g. "404 — Страница
не найдена".
- ErrorPage.tsx: FALLBACK_CONFIG literal instead of ERROR_CONFIG["500"]!
- ErrorBoundary.tsx: hoist FALLBACK_RU / FALLBACK_EN to consts so
pickStrings returns them without the bang.
- routesToPolylines.ts: narrow spider-mode block on filterState.departure
truthy; guard each route-code lookup.
- FlightsMapStartPage.tsx: narrow firstRoute/depCode/arrCode together
instead of asserting each individually.
- OnlineBoardDetailsPage.tsx: IIFE over legs[i+1] for TransferBar;
`_canonicalOrigin` prefix for currently-unused prop.
Warning count: 30 → 19.
Replace the inline 'Invalid parameters' fallbacks and the framework's
default '404' text with the existing Aeroflot 404 screen. Unknown
locale, malformed flight/route/station params, and unmatched URLs
(including bad paths like onlineboard//route/...) now all land on the
same ErrorPage component.
gnezim