Skipping precaching: Cannot read property 'concat' of null`

Here's my question: How might I try to get rid of the 'skipping precaching' and cache everything that comes in from http://ift.tt/1Hdnh4X as the precache list?

Also, is it correct for me to set precache="http://ift.tt/1Hdnh4X" or should I be setting that to a function that grabs the data and returns it instead?

Skipping precaching: Cannot read property 'concat' of null comes out on the console when using My Polymer App

<platinum-sw-cache default-cache-strategy="fastest" cache-config-file="cache-config.json" precache="http://ift.tt/1Hdnh4X">

I am assuming correctly I can precahce a URL like this, right?

I am trying to load a json result from laravel 5.1 to set what my precache should be... I know it's not the most elegant, but I'm new to Polymer, cache, service workers, etc, and using this app as a learning opportunity. It'll be a bit different at the end of the day, but for now I just want to load everything. :)

I want to precache all of the data so that a user can fully utilize this app when offline (though later I'll set it up so that they don't have to precache loads and loads of json requests, only the ones they want, like per book - but that's for later).

via Chebli Mohamed