nst rethrowErrorMessage = 'check this is rethrown';

function assert_not_muted_error_event(error) {
  assert_not_equals(error, undefined, 'should fire error event');
  // Report an error, 6. If script has muted errors, ...
  // https://html.spec.whatwg.org/multipage/webappapis.html#report-the-error
  assert_false(error.event === 'Script error.'
      && error.source === '' && error.lineno === 0 && error.colno === 0
      && error.error === null,
      'the error should not be muted.');
  assert_false(!error