Simple error to Mixpanel tracker

onerror.js

'use strict'

import Mixpanel from 'mixpanel'

let init = () => (window.onerror = catchError)
, trackerFeedback = () => console.info( 'This error has been reported!')
, throwError = function( msg, source, linenumber ){
  if(
    typeof msg === 'string'
    && typeof source === 'string'
    && typeof linenumber === 'number'
  ){
    catchError( msg, source, linenumber )
  }
}
, catchError = function(
  msg = ''
  , source = ''
  , linenumber = -1
  , ...props
){
  if( window.btoa ){
    let payload = { msg, source, linenumber }
    , b64 = window.btoa( JSON.stringify( Object.assign( payload, props ) ) )
    Mixpanel.track(
      "Error"
      , b64
      , trackerFeedback
    )
  }
}

module.exports = { init, throwError }