imported useRef

src/client/js/components/CustomNavigation.jsx

@@ -1,4 +1,4 @@
-import React, { useEffect, useState } from 'react';
+import React, { useEffect, useState, useRef } from 'react';
 import PropTypes from 'prop-types';
 import {
   Nav, NavItem, NavLink, TabContent, TabPane,