fix(blockvalidation): surface metadata fetch error in ValidateBlock instead of assuming valid

services/blockvalidation/BlockValidation.go

@@ -1176,8 +1176,7 @@ func (u *BlockValidation) ValidateBlockWithOptions(ctx context.Context, block *m
 				// Block exists - check if it's invalid
 				_, blockMeta, err := u.blockchainClient.GetBlockHeader(ctx, block.Header.Hash())
 				if err != nil {
-					ctxLogger.Warnf("[ValidateBlock][%s] failed to get block metadata for existing block: %v, assuming valid", block.Header.Hash().String(), err)
-					return nil
+					return errors.NewServiceError("[ValidateBlock][%s] failed to get block metadata for existing block", block.Header.Hash().String(), err)
 				}
 
 				if blockMeta != nil && blockMeta.Invalid {

services/blockvalidation/BlockValidation_metadata_test.go

@@ -0,0 +1,63 @@
+package blockvalidation
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/bsv-blockchain/go-bt/v2/chainhash"
+	txmap "github.com/bsv-blockchain/go-tx-map"
+	"github.com/bsv-blockchain/teranode/errors"
+	"github.com/bsv-blockchain/teranode/model"
+	"github.com/bsv-blockchain/teranode/services/blockchain"
+	"github.com/bsv-blockchain/teranode/ulogger"
+	"github.com/bsv-blockchain/teranode/util/expiringmap"
+	"github.com/bsv-blockchain/teranode/util/test"
+	"github.com/ordishs/gocore"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+func TestValidateBlock_MetadataFetchFailure(t *testing.T) {
+	initPrometheusMetrics()
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+
+	tSettings := test.CreateBaseTestSettings(t)
+	logger := ulogger.TestLogger{}
+
+	nBits, err := model.NewNBitFromSlice([]byte{0x1b, 0x04, 0x86, 0x4c})
+	require.NoError(t, err)
+
+	block := &model.Block{
+		Header: &model.BlockHeader{
+			Version:        1,
+			HashPrevBlock:  &chainhash.Hash{},
+			HashMerkleRoot: &chainhash.Hash{},
+			Timestamp:      uint32(time.Now().Unix()), // nolint:gosec
+			Bits:           *nBits,
+			Nonce:          2083236893,
+		},
+	}
+
+	mockBlockchainClient := &blockchain.Mock{}
+	mockBlockchainClient.On("GetBlockExists", mock.Anything, mock.Anything).Return(true, nil)
+	mockBlockchainClient.On("GetBlockHeader", mock.Anything, mock.Anything).
+		Return(nil, nil, errors.NewServiceError("simulated transient DB outage"))
+
+	bv := &BlockValidation{
+		blockHashesCurrentlyValidated: txmap.NewSwissMap(0),
+		blockExistsCache:              expiringmap.New[chainhash.Hash, bool](120 * time.Minute),
+		blocksCurrentlyValidating:     txmap.NewSyncedMap[chainhash.Hash, *validationResult](),
+		logger:                        logger,
+		settings:                      tSettings,
+		blockchainClient:              mockBlockchainClient,
+		stats:                         gocore.NewStat("test"),
+	}
+	defer bv.blockExistsCache.Stop()
+
+	err = bv.ValidateBlock(ctx, block, "test")
+	require.Error(t, err, "metadata fetch failure must surface as an error, not be swallowed as valid")
+	require.True(t, errors.Is(err, errors.ErrServiceError), "expected ServiceError, got %v", err)
+}