message: ADD check for connect-ability to build storybook / url, throw an human readable error if connect connect
diff: +import fetch from 'node-fetch';
  import denodeify from 'denodeify';
  import { confirm } from 'node-ask';
  import setupDebug from 'debug';
  @@ -350,6 +351,18 @@ export async function runTest({
  debug(`Connecting to ${isolatorUrl} (cachedUrl ${cachedUrl})`);
  + if (
  + await fetch(url)
  + .then(_ => true)
  + .catch(e => {
  + throw new Error(
  + `Storybook was not build succesfully, or provided url (${url}) wasn't reachable, there are likely errors above`
  + );
  + })
  + ) {
  + debug(`connected to ${url} success`);
  + }
  +
  log.info(
  `Uploading and verifying build (this may take a few minutes depending on your connection)`
  );
  