Uncaught TypeError: Cannot read property 'focus' of null

[c-emil]

Hi, there's a problem with calling focus on element that doesn't exists anymore.

The Uncaught TypeError is triggered on this line: https://github.com/selvagsz/react-power-select/blob/master/src/Select.js#L156

The source of the problem is that powerselect element no longer exist but it tries to call the focus method on it. I think the setTimeout should be assigned to an instance variable and once the Select component is about to be destroyed, this timeout should be cleared out.

[c-emil]

Or it can just check whether the element exists and only then call the focus on it. Let me know which option (if any) suits you better and I can submit PR for it.

[selvagsz]

@c-emil we should be clearing the timeout on destroy

[c-emil]

Alright, I'll submit a PR for that once I get to it.