rfq: relay error code in oracle response

Ensure the error code is part of an OracleError response, and pass the
error intact in query{Bid,Ask}FromPriceOracle, instead of formatting it
as a string.

Author: jtobin

rfq/negotiator.go

@@ -146,10 +146,9 @@ func (n *Negotiator) queryBuyFromPriceOracle(assetSpecifier asset.Specifier,
 	}
 
 	// Now we will check for an error in the response from the price oracle.
-	// If present, we will convert it to a string and return it as an error.
+	// If present, we will simply relay it.
 	if oracleResponse.Err != nil {
-		return nil, fmt.Errorf("failed to query price oracle for "+
-			"buy price: %s", oracleResponse.Err)
+		return nil, oracleResponse.Err
 	}
 
 	// By this point, the price oracle did not return an error or a buy
@@ -282,10 +281,9 @@ func (n *Negotiator) querySellFromPriceOracle(assetSpecifier asset.Specifier,
 	}
 
 	// Now we will check for an error in the response from the price oracle.
-	// If present, we will convert it to a string and return it as an error.
+	// If present, we will simply relay it.
 	if oracleResponse.Err != nil {
-		return nil, fmt.Errorf("failed to query price oracle for "+
-			"sell price: %s", oracleResponse.Err)
+		return nil, oracleResponse.Err
 	}
 
 	// By this point, the price oracle did not return an error or a sell

rfq/oracle.go

@@ -370,7 +370,8 @@ func (r *RpcPriceOracle) QuerySellPrice(ctx context.Context,
 
 		return &OracleResponse{
 			Err: &OracleError{
-				Msg: result.Error.Message,
+				Msg:  result.Error.Message,
+				Code: OracleErrorCode(result.Error.Code),
 			},
 		}, nil
 
@@ -481,7 +482,8 @@ func (r *RpcPriceOracle) QueryBuyPrice(ctx context.Context,
 
 		return &OracleResponse{
 			Err: &OracleError{
-				Msg: result.Error.Message,
+				Msg:  result.Error.Message,
+				Code: OracleErrorCode(result.Error.Code),
 			},
 		}, nil