error 400 bad request code example

Example 1: 400 http

400 Bad Request 

The HyperText Transfer Protocol (HTTP) 400 Bad Request 
response status code indicates that the server cannot or will not 
process the request due to something that is perceived to be a client error
(e.g., malformed request syntax, invalid request message framing, or deceptive request routing).

Example 2: error: request failed with status code 400

You should add a catch to the get call:

import axios from 'axios';
import config from './config';

axios.get('${config.serverUrl/api/contests')
  .then(resp=>{
    console.log(resp.data);
  })  
  .catch(error=>{

  });