I am getting: ReferenceError: jsonObject is not defined in my console when using fetch to test POST submission form data to a test API endpoint

I am just beginning to learn javascript and am hung up on getting my code to POST submission data to a test api endpoint. My console is telling me ReferenceError: jsonObject is not defined. Please help, thanks

<form id="jobData" method="post">
    <fieldset>
        <label for="machineField">Heavy Equipment Machine Type</label>
        <input name="Machine" type="text"" id="machineField">
        </input>
        <label for="workField">Work To Be Performed</label>
        <input type="text"  name="work" id="workField">
        <label for="detailsField">Other Important Details</label>
        <textarea name="details" id="detialsField" cols="30" rows="10"></textarea>
        <button type="submit" name="submit">SEND</button>
    </fieldset>
</form>
<script>
    const url = "https://6fp4lq4r8d.api.quickmocker.com";
    const formEl = document.querySelector("form");
    formEl.addEventListener("submit", async (e) => {
      e.preventDefault();
      const formData = new FormData(formEl);
      const formDataSerialized = Object.fromEntries(formData);
      console.log(formDataSerialized, "formDataSerialized");
      try {
          const response = await fetch(url, {
              method: 'POST',
              body: JSON.stringify(jsonObject),
              headers: {
                  'Content-Type': 'application/jason'
              }
          });
          const json = await response.json();
          console.log(json);
      } catch(e){
          console.error(e);
          alert("An Error Occured");
      }
    });
</script>