Graceful graph load failures

In the graph list:

* catch any img load failures
* hide the broken imgs
* hide the spinners
* set a background color, add a (somewhat) helpful message, and link to the graph profile

In the graph profile:

* catch an img load failure
* hide the broken img
* hide the spinner
* set a background color and add a friendly background img

In an unrelated commit that I forgot snuck in here, added a handful of proper halts in failure cases.