can't able to get email from github api users

I'm using token which gives me the email of GitHub users but still some of them shows me null.

I also tried my own GitHub account but get email:null.

I also set my email to public in Github profile still it gives me null.

After that I tried to use client-id and secret_key but then the request gets failed.

If i can get these emails through client-id and secret_key please tell me how to use this in my header. (as shown in comment)

export const fetchingGithubUserProfile = (GithubUsername) => {
       const REQUEST = `https://api.github.com/users/${GithubUsername}`
       const client_id = 'xxxxxxxxxxxxxx'
       const client_secret = 'xxxxxxxxxxxxxxxxx';
       var config = { 
           headers: {
               'Authorization': 'token xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx '
             // "Authorization": "token xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" + btoa(client_id + ':' + 
                  client_secret),
             // 'ID' : 'Client ID e711e8d32ba8aea7c60f',
             // 'Secret' : 'Client Secret b52543a7c2090f6a10725ac75f2dec03fbe4e2c9',
            }
          }
            return dispatch => {
              axios.get(REQUEST,config)
                .then(res => { 
                   dispatch(fetchedGithubUserProfileSuccess(res.data))
                 })
                 .catch(err => {
                   console.log(err)
                })
             }
           }