message: improved error messages if server fails to start during test suite
diff: @@ -5,6 +5,7 @@ const fs = require('fs');
  const quickTemp = require('quick-temp');
  const { WatchedDir } = require('broccoli-source');
  const Funnel = require('broccoli-funnel');
  +const log = require('@cardstack/plugin-utils/logger')('hub/main');
  module.exports = {
  name: '@cardstack/hub',
  @@ -56,7 +57,17 @@ module.exports = {
  testemMiddleware(app) {
  let seedDir = path.join(this.seedPath, 'test');
  let handler;
  - this._middleware(seedDir, null, true, 'test').then(h => handler = h);
  + this._middleware(seedDir, null, true, 'test').then(
  + h => { handler = h; },
  + error => {
  + log.error("Server failed to start. %s", error);
  + handler = (req, res) => {
  + res.status = 500;
  + res.send("@cardstack/hub server failed to start due to exception: " + error);
  + res.end();
  + };
  + }
  + );
  app.use('/cardstack', (req, res) => {
  if (handler) {
  handler(req, res);
  