Handle basic error case in populate item details

If the populate request comes back with any errors, log the errors and
re-render the main page.  This doesn't display much help to the user
other than the console, but it's better than just sitting there forever
waiting.
Refactor find content on page

Pull out the logic that finds the content on the page to it's own
function.  Pass in the selectors that we'd like to try as an array, and
loop over those until we find content, or we've tested each selector.