Nextjs Middleware to redirect

import { NextResponse } from 'next/server'
import type { NextRequest } from 'next/server'

export function middleware(req: NextRequest) {
  if (req.nextUrl.pathname === '/') {
    return NextResponse.redirect('/dashboard')
  }
}

Error: URLs is malformed. Please use only absolute URLs - https://nextjs.org/docs/messages/middleware-relative-urls