UNEXPECTED END OF JSON INPUT from querying data from headless cms Nextjs

here is my code for getting data from a graphql query from a headless CMS. It seems though that even though the query is being fetched without error, it creates the "UNEXPECTED END OF JSON INPUT". Occurs when parsing into JSON so I can pass the data to my page.

const URL = process.env.STRAPIBASEURL;

export async function getStaticProps(context) {
  const fetchParams = {
    method: "posts",
    headers: {
      "content-type": "application/json",
    },
    body: JSON.stringify({
      query: `{
        blogposts{
          title
          content
          slug
          img{
            url
          }
        }
      }`,
    }),
  };
  const res = await fetch(`${URL}/graphql`, fetchParams);

  const data = await res.json();
  return {
    props: data,
  };
}