My proposal is to change definition of JobLog to:

data JobLog = JobLog
  { _scst_succeeded :: !Int
  , _scst_failed    :: !Int
  , _scst_remaining :: !Int
  , _scst_events    :: ![ScraperEvent]
  }

i.e. remove Maybe in all these fields. Also, for ScraperEvent:

data ScraperEvent = ScraperEvent
  { _scev_message :: !Text
  , _scev_level   :: !Text
  }

i.e. remove Maybe's as well. Also, I don't see any usages of _scev_date and I propose to remove it, because it requires going into the IO monad to fetch current time.

The reasons for this are justified in !429 (comment 14838).

Also, make JobLog a Semigroup instance so we can remove noJobLog and just use mempty. We could redefine G.A.Jobs a bit. E.g. instead of having addErrorEvent, addWarningEvent, addEvent we could just have:

myJobLog <> (mkEvent "ERROR" msg)

where

mkEvent lvl msg = JobLog 0 0 0 [ ScraperEvent msg lvl ]