Do not require urlBase and siteId if matomo is disabled

[KrzysztofMadejski]

I have urlBase: '', siteId: '', disabled: true, but I'm getting the following

Error: Matomo urlBase is required.
new MatomoTracker
src/MatomoTracker.ts:20
  17 |     }
  18 |     if (!userOptions.siteId) {
  19 |         throw new Error('Matomo siteId is required.');
> 20 |     }
     | ^  21 |     this.initialize(userOptions);
  22 | }
  23 | initialize({ urlBase, siteId, userId, trackerUrl, srcUrl, disabled, heartBeat, linkTracking = true, configurations = {}, }) {
View compiled
createInstance
src/instance.ts:5
  2 | function createInstance(params) {
  3 |     return new MatomoTracker(params);
  4 | }
> 5 | export default createInstance;
  6 | //# sourceMappingURL=instance.js.map
View compiled

I'd expect matomo-tracker not to throw errors.