#### Summary

It would be nice to export a typeguard from Axios' index.d.ts.
This way, consumers trying to do error handling can check in a type-safe way if the error is an AxiosError, or some other kind of error.

It's easy enough to do this as a consumer, but it would be nicer if this was included in the actual Axios library.

test/specs/instance.spec.js
jasmine.Ajax.install();
  });
  afterEach(function () {
    jasmine.Ajax.uninstall();
  });
  it('should have the same methods as default instance', function () {
    var instance = axios.create();
    for (var prop in axios) {
      if ([
        'Axios',
        'create',
        'Cancel',
        'CancelToken',
        'isCancel',
        'all',
        'spread',
        'default'].indexOf(prop) > -1) {
        continue;
      }
      expect(typeof instance[prop]).toBe(typeof axios[prop]);
    }
  });
  it('should make an http request without verb helper', function (done) {
    var instance = axios.create();
    instance('/foo');
    getAjaxRequest().then(function (request) {
      expect(request.url).toBe('/foo');
      done();
    });
  });