Add if check before using cursor

[didia]

Requirements

Filling out this template is required.

• Have you viewed your changes locally on the demos page, located on https://github.com/mattboldt/typed.js/blob/master/index.html?

• If necessary, have you added a new demo to the index.html list of demos? If it's an improvement or small addition, have you added it to an existing demo on the demos page?

• If applicable, have you created a fork of the following JSFiddle with your branch's code and your new feature showcased?

  • Before: https://jsfiddle.net/thefuture2092/usued699/1/
  • After: https://jsfiddle.net/thefuture2092/ezpmz1vu/2/

Description of the Change

Right now, if you set option fadeOut: true and showCursor: false we have an error because we are trying to add the fadeOutClass to the cursor.className while the cursor does not exist.

I have added if checks to check if the cursor exist before using it.

Benefits

No errors and the fadeout is usable without the cursor. Cheers 🎉

Issues

[mattboldt]

Thank you very much! And I really appreciate you making demos and detailing all your changes.