Converting JWT callbacks to promises

jwt.ts

import jwt from "jsonwebtoken";

export function tokenService() {
  const SECRET = "secret";
  return new Promise<string>((resolve, reject) => {
    jwt.sign(
      { foo: "bar" },
      SECRET,
      (err: Error, token: string) => {
        if (err) reject(err);
        resolve(token);
      },
    );
  });
}