What is the intention of this following code?

Hi, I wonder to know what is the intention of this following code? Thanks.

function vuePlugin(Raven, Vue) {
  ...
  // what is the intention of this following code?
  var _oldOnError = Vue.config.errorHandler;
  Vue.config.errorHandler = function VueErrorHandler(error, vm, info) {
    ...
    if (typeof _oldOnError === 'function') {
      // what is the intention of this following code?
      _oldOnError.call(this, error, vm, info);
    }
  };
}

Above code comes from here

[xxxsf]

All right, thank you very much for answering my question.

[kamilogorek]

It will, but there are a lot of people who still want to see the logs locally during development. See: https://github.com/getsentry/sentry-javascript/issues/2018