Next.js build failing

app/api/auth/[...all]/route.ts
Type error: Route "app/api/auth/[...all]/route.ts" has an invalid export:
  "unknown" is not a valid GET return type:
    Expected "void | Response | Promise<void | Response>", got "unknown".

Next.js build worker exited with code: 1 and signal: null

import { auth } from "@/lib/auth/server";
import { toNextJsHandler } from "better-auth/next-js";

export const { GET, POST } = toNextJsHandler(auth);