Fix hanling of missing tx in Zcash block 0

bchain/coins/zec/zcashrpc.go

@@ -80,7 +80,7 @@ func (z *ZCashRPC) GetBlock(hash string, height uint32) (*bchain.Block, error) {
 	for _, txid := range res.Result.Txids {
 		tx, err := z.GetTransaction(txid)
 		if err != nil {
-			if isInvalidTx(err) {
+			if err == bchain.ErrTxNotFound {
 				glog.Errorf("rpc: getblock: skipping transanction in block %s due error: %s", hash, err)
 				continue
 			}
@@ -95,20 +95,6 @@ func (z *ZCashRPC) GetBlock(hash string, height uint32) (*bchain.Block, error) {
 	return block, nil
 }
 
-func isInvalidTx(err error) bool {
-	switch e1 := err.(type) {
-	case *errors.Err:
-		switch e2 := e1.Cause().(type) {
-		case *bchain.RPCError:
-			if e2.Code == -5 { // "No information available about transaction"
-				return true
-			}
-		}
-	}
-
-	return false
-}
-
 // GetTransactionForMempool returns a transaction by the transaction ID.
 // It could be optimized for mempool, i.e. without block time and confirmations
 func (z *ZCashRPC) GetTransactionForMempool(txid string) (*bchain.Tx, error) {