refactor: address double-sign review feedback

Author: CaelRowley

block/internal/syncing/doublesign.go

@@ -105,16 +105,12 @@ func reportDoubleSign(
 	firstHashStr := ev.FirstHeader.Hash().String()
 	key := store.GetDoubleSignEvidenceKey(ev.Height, ev.AlternateHeader.Hash())
 
-	// Persist on every call: idempotent, and a retry covers a transient
-	// failure on the first attempt.
-	persistErr := persistEvidence(ctx, st, ev)
-
 	if seen != nil && !seen.markSeen(ev.Height, altHashStr) {
 		return nil
 	}
 
-	if persistErr != nil {
-		logger.Error().Err(persistErr).
+	if err := persistEvidence(ctx, st, ev); err != nil {
+		logger.Error().Err(err).
 			Uint64("height", ev.Height).
 			Str("first_hash", firstHashStr).
 			Str("alternate_hash", altHashStr).

block/internal/syncing/syncer.go

@@ -1088,7 +1088,8 @@ func (s *Syncer) detectDoubleSign(ctx context.Context, header *types.SignedHeade
 	}
 	prior, priorSource, err := firstObservation(ctx, s.store, s.cache, header.Height())
 	if err != nil {
-		s.logger.Warn().Err(err).Uint64("height", header.Height()).Msg("double-sign detection error")
+		// Detection bypassed for this observation, still cached below so a later arrival can match against this header
+		s.logger.Error().Err(err).Uint64("height", header.Height()).Msg("double-sign detection bypassed")
 	} else if ev := buildEvidenceFromPair(prior, header, priorSource, source); ev != nil {
 		s.handleDoubleSign(ctx, ev)
 		return true