Fix crashing server

[curran]

ypeError: Cannot read property 'text' of undefined
  File "/home/ubuntu/vizhub/packages/ui/dist/index.js", line 527, in extractTitle
    var titleMatch = htmlFile.text.match(/<title>(.*?)<\/title>/i);
  File "/home/ubuntu/vizhub/packages/ui/dist/index.js", line 539, in MapSubscriber.project
    operators.map(function (action) { return setTitle(extractTitle(getFile(state$.value, 'index.html'))); }
  File "/home/ubuntu/vizhub/packages/web/.next/server/bundles/pages/visualization.js", line 1635, in new _default
    _this.store.dispatch(initFiles(files));
  File "/home/ubuntu/vizhub/packages/web/.next/server/bundles/pages/_document.js", line 173, in Function._callee$