Differentiate NO_FCP failure cases

I'm encountering an issue when running Lighthouse from DevTools: for many performance metrics I get an audit error "No usable `firstMeaningfulPaint(Candidate)` events found in trace". However there's really not too much going on the page, so I'm not sure why it is happening.


However when I run Lighthouse as a Chrome Extension instead I don't get these errors. I've included the JSON export for Lighthouse in DevTools and then as an Extension below.

If there's any other information you'd like, just let me know!

[Lighthouse DevTools JSON export](https://jsonblob.com/e207e8b8-ed5d-11e7-8022-73e99ed1aa46)
[Lighthouse Extension JSON export](https://jsonblob.com/7e27fadc-ed5d-11e7-8022-f94fe8193b49)