Can't print data from the Yandex.Weather server?

Question

JavaScript

Can't print data from the Yandex.Weather server?
Yandex has poor documentation + I have little experience to figure it out myself.
Please help me if I'm accessing the API correctly, if it's correct why it doesn't print out json.

getWeather(){
  return new Promise((resolve,reject) => {
    fetch(this.uri,{
      method: 'GET',
      headers: {
        'Content-type': 'application/json',
        'X-Yandex-API-Key': this.apiKey
      }
    })
.then(res => res.json()) // <--- Ошибка?
.then(data => resolve(data))
.catch(err => reject(err));
  });
}