message: frontend: Fix JS error when closing modals with Cancel link
  "React DOM tree root should always have a node reference" errors were
  being thrown when a modal Cancel link was clicked.
diff: @@ -41,9 +41,13 @@ export const ModalFooter = ({message, errorMessage, inProgress, children}) => {
  };
  export const ModalSubmitFooter = ({message, errorMessage, inProgress, cancel, submitText, submitDisabled}) => {
  + const onCancelClick = e => {
  + e.stopPropagation();
  + cancel();
  + };
  return <ModalFooter inProgress={inProgress} errorMessage={errorMessage} message={message}>
  <button type="submit" className="btn btn-primary" disabled={submitDisabled}>{submitText}</button>
  - <button type="button" onClick={cancel} className="btn btn-link">Cancel</button>
  + <button type="button" onClick={onCancelClick} className="btn btn-link">Cancel</button>
  </ModalFooter>;
  };
  