"Creating undefined" title on some pages

[pdehaan]

Found in https://pageshot.net/__version__ (848ad59):

{
  "source": "https://github.com/mozilla-services/pageshot/",
  "description": "Page Shot application server",
  "version": "October 04, 2016 18:05:16 UTC",
  "commit": "848ad59",
  "contentOrigin": "pageshot-usercontent.net",
  "commitLog": "https://github.com/mozilla-services/pageshot/commits/848ad59",
  "unincludedCommits": "https://github.com/mozilla-services/pageshot/compare/848ad59...master"
}

---

Randomly spotted this while looking at Activity Stream and seeing a few Page Shot entries with titles saying "Creating undefined":

[ianb]

I can't reproduce this, so I don't quite know why it happens. But I'm changing the creating page to use 'page', like 'Creating page', if it can't find the title for some reason.