NO_SCREENSHOTS on every run

[connorjclark]

Mac Mojave, Stable Chrome 74.0.3729.169

Error was introduced between 4.2 / 4.3

# works
npx -p lighthouse@4.2 lighthouse https://www.example.com --view
# no works
npx -p lighthouse@4.3 lighthouse https://www.example.com --view

Stable DevTools is fine b/c it's still 4.2 Canary is not b/c it's 4.3.1.

See the same error with master in ToT Chrome.

[connorjclark]

this doesn't occur any more.