Any Idea why it won't work?

[Isak-Taun]

TypeError: Cannot read property 'get' of undefined
fetchExistingTasks @ Code.gs:65

[Erick-Bryan-Cubas]

This error can occur if the object is not defined properly or if the property is not set. To fix this error, make sure that you have defined the object and that it has the property set correctly.templateParams_gettemplateParams_get

const templateParams = {
  _post: {
    method: "post",
    headers: { "x-api-user": HABITICA_ID, "x-api-key": HABITICA_TOKEN },
  },
  _get: {
    contentType: "application/json",
    method: "get",
    headers: { "x-api-user": HABITICA_ID, "x-api-key": HABITICA_TOKEN },
  },
  _delete: {
    method: "delete",
    headers: { "x-api-user": HABITICA_ID, "x-api-key": HABITICA_TOKEN },
  },
};