Using keyboard for intro navigation breaks on the last step

[jaimefps]

Description

Describe one (and only one) issue or enhancement you want to see in Intro.js (before writing any code).

If I use my keyboard to move through steps in the intro, then Intro.js auto-focuses the "next" button so all that the user needs to do is continue hitting the "enter" button to move forward. That works find, except on the very last step, where it seems that even though the Next is hidden, it still holds focus, and hitting "Enter" on the keyboard breaks everything as it attempts to reach a non-existent step.

This can be a problem for keyboard users / accessibility.

Expected Behavior

What did you expect to happen?

I expect that the "Done" button is what is auto-focused on the last step and simply finishes the demo when I continue hitting "enter".

Actual Behavior

What actually happened?

Intro.js breaks on the last step

Errors and Screenshots (optional)

Give us any additional information if you have.

Example (recommended)

How can someone else see/test this issue? List the steps or write some code; or create a jsfiddle or codepen.

Environment (optional)

List browser information, Intro.js version, Operating System, JavaScript libraries (jQuery, Angular, React), etc.