Unhandled exception in request() method of class Client

[dentakoy]

Hello!
I find unhandled exception in request() method of class Client.
File src/client.ts line 33

  request(command: string, body?: any) {
    const url = `${this.address}/api/${command}`;
    let init;
    if (body) {
      init = {
        method: 'POST',
        headers: {
          Accept: 'application/json',
          'Content-Type': 'application/json'
        },
        body: JSON.stringify(body)
      };
    }
    return new Promise((resolve, reject) => {
      fetch(url, init)
        .then((res) => {
          if (res.ok) return resolve(res.json());
          throw res;
        })
        // line with unhandled exception: .catch((e) => e.json().then((json) => reject(json)));
        // my fix:
        .catch((e) => {
          e.json()
            .then((json)  => reject(json))
            .catch((e)    => reject(e))
        });
    });
  }