message: fix(writer): Fix succeeded flash count in progress state
  This fixes a bug where succeeded flashes could become negative due to
  improper math
  Change-Type: patch
diff: @@ -397,6 +397,7 @@ class ImageWriter extends EventEmitter {
  state.flashing += !dest.error && !dest.finished ? 1 : 0
  state.verifying += !dest.error && dest.finished && !dest.verified ? 1 : 0
  state.failed += dest.error ? 1 : 0
  + state.succeeded += !dest.error && dest.finished && (dest.verified || !this.verifyChecksums) ? 1 : 0
  if (!(dest.finished && dest.verified) && !dest.error) {
  state.totalSpeed += state.type === 'write'
  ? dest.stream.speed
  @@ -409,7 +410,6 @@ class ImageWriter extends EventEmitter {
  ? state.totalSpeed / state.active
  : state.active
  - state.succeeded = state.active - state.failed - state.flashing - state.verifying
  state.eta = state.speed ? state.remaining / state.speed : 0
  this.emit('progress', state)
  