render() {
		L.error('InternalError', 'Not implemented');
	}
Render the form element.

The `render()` function recursively walks the form element tree and
renders the markup for each element, returning the assembled DOM tree.

@abstract
@returns {Node|Promise<Node>}
May return a DOM Node or a promise resolving to a DOM node containing
the form element's markup, including the markup of any child elements.