Update step element proptype

Author: HiDeoo

src/components/Steps/index.js

@@ -19,7 +19,10 @@ export default class Steps extends Component {
     initialStep: PropTypes.number.isRequired,
     steps: PropTypes.arrayOf(
       PropTypes.shape({
-        element: PropTypes.oneOfType([PropTypes.string, PropTypes.element]),
+        element: PropTypes.oneOfType([
+          PropTypes.string,
+          typeof Element === 'undefined' ? PropTypes.any : PropTypes.instanceOf(Element),
+        ]),
         intro: PropTypes.node.isRequired,
         position: introJsPropTypes.tooltipPosition,
         tooltipClass: PropTypes.string,