"published_at" of a product can be null
"handle": "webcomic-science-valentines",
"template_suffix": null,
"updated_at": "2015-02-10T14:54:37-05:00",
"published_at": null,
"created_at": "2015-01-26T12:14:49-05:00",
"published_scope": "global",
"id": 410963172,
This happens when something isn't currently published.