function initClient() {
  window.gapi.client.init(googleCalendarConfig)
  .then(_ => {
    console.log('init ok')
  })
  .catch(error => {
    dispatch('authenticationError', {error, note: 'Error on GAPI init.'})
  })
}
window.gapi.load('client', initClient)

googleyolo.retrieve(oneTapConfig)
.then(credential => {
  console.log('credential → ', credential)
  let token = {access_token: credential.idToken}
  window.gapi.client.setToken(token)
})

gapi.client.calendar.events.list({
  calendarId: "primary",
  timeMin: new Date().toISOString(),
  showDeleted: false,
  singleEvents: true,
  maxResults: 10,
  orderBy: "startTime"
})

{
 "error": {
  "errors": [
   {
    "domain": "global",
    "reason": "authError",
    "message": "Invalid Credentials",
    "locationType": "header",
    "location": "Authorization"
   }
  ],
  "code": 401,
  "message": "Invalid Credentials"
 }
}