Add checker for no transaction cost

code/go/0chain.net/chaincore/block/entity.go

@@ -52,6 +52,7 @@ var (
 	ErrPreviousStateUnavailable = common.NewError("prev_state_unavailable", "Previous state not available")
 	ErrPreviousStateNotComputed = common.NewError("prev_state_not_computed", "Previous state not computed")
 	ErrCostTooBig               = common.NewError("cost_too_big", "Block cost is too big")
+	ErrCostNotFound             = common.NewError("cost_not_found", "Cost if not defined for transaction")
 
 	// ErrPreviousBlockUnavailable - error for previous block is not available.
 	ErrPreviousBlockUnavailable = common.NewError(PreviousBlockUnavailable,

code/go/0chain.net/miner/protocol_block.go

@@ -33,6 +33,8 @@ import (
 // InsufficientTxns - to indicate an error when the transactions are not sufficient to make a block
 const InsufficientTxns = "insufficient_txns"
 
+const NoTransactionCost = "no_transaction_cost"
+
 // ErrLFBClientStateNil is returned when client state of latest finalized block is nil
 var ErrLFBClientStateNil = errors.New("client state of latest finalized block is empty")
 
@@ -353,6 +355,9 @@ func (mc *Chain) VerifyBlock(ctx context.Context, b *block.Block) (
 			if err != nil {
 				return err
 			}
+			if c == math.MaxInt {
+				return block.ErrCostNotFound
+			}
 
 			cost += c
 			costs = append(costs, c)
@@ -1171,6 +1176,10 @@ func (mc *Chain) generateBlock(ctx context.Context, b *block.Block,
 			logging.Logger.Debug("Bad transaction cost", zap.Error(err), zap.String("txn_hash", txn.Hash))
 			break
 		}
+		if cost == math.MaxInt {
+			logging.Logger.Debug("No transaction cost", zap.Error(err), zap.String("txn_hash", txn.Hash))
+			return common.NewError(NoTransactionCost, fmt.Sprintf("No transaction cost for txn %v", txn.Hash))
+		}
 		if iterInfo.cost+cost >= mc.ChainConfig.MaxBlockCost() {
 			logging.Logger.Debug("generate block (too big cost, skipping)")
 			break