vue3 vitest mock axios can't read 'then'

I have the function in the Races.vue file, the front end is working fine but not testing

getRaces: function () {
  axios.get(URL)
      .then(response => {
        console.log(response)
      })
      .catch(error => {
        console.log(error);
        this.errored = true;
      })
      .finally(() => {
        this.loading = false;
      })
}

And when I try to test it, after adding vi.mock part, will give "TypeError: Cannot read properties of undefined (reading 'then')" error

import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest'
import { shallowMount, mount, flushPromises } from '@vue/test-utils'
import Races from '../Races.vue'
import axios from 'axios'

vi.mock("axios", () => {
  return {
    default: {
      get: vi.fn(),
    },
  };
});

Any idea on how to solve this? Thank you so much