Runtime error when tabbing elements where shadowDom is a document fragment rather than an element

[majornista]

el.activeElement in the following method will be null if el is a document fragment rather than an element, which throws a runtime error:

react-modal/src/helpers/scopeTab.js

Lines 3 to 7 in a275399

	function getActiveElement(el = document) {
	return el.activeElement.shadowRoot
	? getActiveElement(el.activeElement.shadowRoot)
	: el.activeElement;
	}