setel ulang keadaan reaktif vue 3

// this not working for me if i have nasted array of object in intialState not sure way  
setup() {
    const initialState = {
      name: "",
      lastName: "",
      email: ""
    };

    const form = reactive({ ...initialState });

    function resetForm() {
      Object.assign(form, initialState);
    }

    function setForm() {
      Object.assign(form, {
        name: "John",
        lastName: "Doe",
        email: "[email protected]"
      });
    }

    return { form, setForm, resetForm };
  }
code fighter