Fix real Biome bugs: inner declarations, dup keys, assign-in-expr, implicit any, cookie, a11y svg/keyboard, json

src/app/error.tsx

@@ -8,7 +8,7 @@ import { useEffect } from "react";
  * stays), shows a friendly card, and offers a reset. The raw error is logged to
  * the console, never shown to the user.
  */
-export default function Error({
+export default function ErrorPage({
 	error,
 	reset,
 }: {