Vite 4.0.0 bug

See vitejs/vite#13730

Use pnpm 8 and latest Node.js 20.
pnpm install
ui/start.tsx
Open http://localhost:5173 and see "Invalid URL" in the console.
Upgrade to vite 4.0.1 in package.json and see the error go away.
Opening http://localhost:5173 should print It works to the browser devtools.