How to use the single-spa.addErrorHandler function in single-spa

beforeEach(() => {
    errs = [];
    singleSpa.addErrorHandler(handleError);

    /* See http://jasmine.github.io/2.1/introduction.html#section-Asynchronous_Support.
     * Sometimes saucelabs is so slow on this test that jasmine times out
     */
    ogJasmineTimeout = jasmine.DEFAULT_TIMEOUT_INTERVAL;
    jasmine.DEFAULT_TIMEOUT_INTERVAL = 10000;

    location.hash = '#';

    return import('./unmount-times-out.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })

beforeEach(() => {
    location.hash = activeHash;

    errs = [];
    singleSpa.addErrorHandler(handleError);

    return import('./invalid-no-unmount.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })

beforeEach(() => {
    location.hash = '#'

    errs = [];
    singleSpa.addErrorHandler(handleError);

    return import('./bootstrap-times-out.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })

beforeEach(() => {
    location.hash = '';

    errs = [];
    singleSpa.addErrorHandler(handleError);

    return singleSpa.triggerAppChange()
  });

beforeEach(() => {
    location.hash = `#`;

    errs = [];
    singleSpa.addErrorHandler(handleError);

    return import('./mount-fails.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })

beforeEach(() => {
    errs = [];
    singleSpa.addErrorHandler(handleError);

    return import('./invalid-mount.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })

beforeEach(() => {
    location.hash = '#';

    errs = [];
    singleSpa.addErrorHandler(handleError);

    return import('./unmount-times-out-dies.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })

beforeEach(() => {
    location.hash = "#";
    errs = [];
    singleSpa.addErrorHandler(handleError);
  });

beforeEach(() => {
    location.hash = '#';

    errs = [];
    singleSpa.addErrorHandler(handleError);

    return import('./unmount-rejects.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })

beforeEach(() => {
    location.hash = activeHash;

    errs = [];
    singleSpa.addErrorHandler(handleError);

    return import('./invalid-no-bootstrap.app.js')
      .then(app => myApp = app)
      .then(app => app.reset())
  })