ethclient: Fix RPC parse error of Parity response

The error produced when using a Parity RPC was the following:

ERROR: transaction did not get mined: failed to get tx for txid 0xbdeb094b3278019383c8da148ff1cb5b5dbd61bf8731bc2310ac1b8ed0235226: json: cannot unmarshal non-string into Go struct field txExtraInfo.blockHash of type common.Hash

Author: stevenroose

ethclient/ethclient.go

@@ -141,7 +141,9 @@ func (ec *Client) getBlock(ctx context.Context, method string, args ...interface
 	// Fill the sender cache of transactions in the block.
 	txs := make([]*types.Transaction, len(body.Transactions))
 	for i, tx := range body.Transactions {
-		setSenderFromServer(tx.tx, tx.From, body.Hash)
+		if tx.From != nil {
+			setSenderFromServer(tx.tx, *tx.From, body.Hash)
+		}
 		txs[i] = tx.tx
 	}
 	return types.NewBlockWithHeader(head).WithBody(txs, uncles), nil
@@ -174,9 +176,9 @@ type rpcTransaction struct {
 }
 
 type txExtraInfo struct {
-	BlockNumber *string
-	BlockHash   common.Hash
-	From        common.Address
+	BlockNumber *string         `json:"blockNumber,omitempty"`
+	BlockHash   *common.Hash    `json:"blockHash,omitempty"`
+	From        *common.Address `json:"from,omitempty"`
 }
 
 func (tx *rpcTransaction) UnmarshalJSON(msg []byte) error {
@@ -197,7 +199,9 @@ func (ec *Client) TransactionByHash(ctx context.Context, hash common.Hash) (tx *
 	} else if _, r, _ := json.tx.RawSignatureValues(); r == nil {
 		return nil, false, fmt.Errorf("server returned transaction without signature")
 	}
-	setSenderFromServer(json.tx, json.From, json.BlockHash)
+	if json.From != nil && json.BlockHash != nil {
+		setSenderFromServer(json.tx, *json.From, *json.BlockHash)
+	}
 	return json.tx, json.BlockNumber == nil, nil
 }
 
@@ -244,7 +248,9 @@ func (ec *Client) TransactionInBlock(ctx context.Context, blockHash common.Hash,
 			return nil, fmt.Errorf("server returned transaction without signature")
 		}
 	}
-	setSenderFromServer(json.tx, json.From, json.BlockHash)
+	if json.From != nil && json.BlockHash != nil {
+		setSenderFromServer(json.tx, *json.From, *json.BlockHash)
+	}
 	return json.tx, err
 }