Send newHeads event only if store succeded for sure

and the block is available for users to query via RPC

blockchain/blockchain.go

@@ -320,7 +320,7 @@ func (b *Blockchain) SetL1Head(update *core.L1Head) error {
 func (b *Blockchain) Store(block *core.Block, blockCommitments *core.BlockCommitments,
 	stateUpdate *core.StateUpdate, newClasses map[felt.Felt]core.Class,
 ) error {
-	return b.database.Update(func(txn db.Transaction) error {
+	err := b.database.Update(func(txn db.Transaction) error {
 		if err := verifyBlock(txn, block); err != nil {
 			return err
 		}
@@ -330,7 +330,6 @@ func (b *Blockchain) Store(block *core.Block, blockCommitments *core.BlockCommit
 		if err := StoreBlockHeader(txn, block.Header); err != nil {
 			return err
 		}
-		b.newHeads.Send(block.Header)
 
 		for i, tx := range block.Transactions {
 			if err := storeTransactionAndReceipt(txn, block.Number, uint64(i), tx,
@@ -356,6 +355,10 @@ func (b *Blockchain) Store(block *core.Block, blockCommitments *core.BlockCommit
 		heightBin := core.MarshalBlockNumber(block.Number)
 		return txn.Set(db.ChainHeight.Key(), heightBin)
 	})
+	if err == nil {
+		b.newHeads.Send(block.Header)
+	}
+	return err
 }
 
 // VerifyBlock assumes the block has already been sanity-checked.