Fix error handling after Browsertime upgrade.
Fix error handling after Browsertime upgrade.

Make sure to include url in error message that's posted on the queue.

JeroenVdb/sitespeed.io,beenanner/sitespeed.io,sitespeedio/sitespeed.io,sitespeedio/sitespeed.io,sitespeedio/sitespeed.io,JeroenVdb/sitespeed.io,sitespeedio/sitespeed.io,beenanner/sitespeed.io,beenanner/sitespeed.io,JeroenVdb/sitespeed.io