react-beautiful-dnd/src/view/throw-if-invalid-inner-ref.js

Beautiful, accessible drag and drop for lists with React.js

// @flow
import invariant from 'tiny-invariant';

export default (ref: ?mixed) => {
  invariant(
    ref && ref instanceof HTMLElement,
    `
    provided.innerRef has not been provided with a HTMLElement.

    You can find a guide on using the innerRef callback functions at:
    https://github.com/atlassian/react-beautiful-dnd/blob/master/docs/guides/using-inner-ref.md
  `,
  );
};