Use set_tx_error consistently to indicate tx errors

Author: jgriffiths

src/ga_tx.cpp

@@ -24,13 +24,6 @@ namespace sdk {
         static const std::string UTXO_SEL_DEFAULT("default"); // Use the default utxo selection strategy
         static const std::string UTXO_SEL_MANUAL("manual"); // Use manual utxo selection
 
-        static void set_tx_error(nlohmann::json& result, const std::string& error)
-        {
-            if (json_get_value(result, "error").empty()) {
-                result["error"] = error;
-            }
-        }
-
         static void add_paths(ga_session& session, nlohmann::json& utxo)
         {
             const uint32_t subaccount = json_get_value(utxo, "subaccount", 0u);
@@ -426,8 +419,7 @@ namespace sdk {
             const bool is_liquid = net_params.is_liquid();
             const auto policy_asset = is_liquid ? net_params.policy_asset() : std::string("btc");
 
-            auto& error = result["error"];
-            error = std::string(); // Clear any previous error
+            result["error"] = std::string(); // Clear any previous error
             result["user_signed"] = false;
             result["server_signed"] = false;
             result["liquid"] = is_liquid;

src/transaction_utils.cpp

@@ -289,6 +289,14 @@ namespace sdk {
         return script;
     }
 
+    void set_tx_error(nlohmann::json& result, const std::string& error)
+    {
+        auto error_p = result.find("error");
+        if (error_p == result.end() || error_p->get<std::string>().empty()) {
+            result["error"] = error;
+        }
+    }
+
     amount add_tx_output(const network_parameters& net_params, nlohmann::json& result, wally_tx_ptr& tx,
         const std::string& address, amount::value_type satoshi, const std::string& asset_id)
     {
@@ -336,12 +344,12 @@ namespace sdk {
             const bool has_assetid = bip21_params.contains("assetid");
 
             if (!has_assetid && bip21_params.contains("amount")) {
-                result["error"] = res::id_invalid_payment_request_assetid;
+                set_tx_error(result, res::id_invalid_payment_request_assetid);
                 return std::string();
             } else if (has_assetid) {
                 const std::string assetid_hex = bip21_params["assetid"];
                 if (!validate_hex(assetid_hex, ASSET_TAG_LEN)) {
-                    result["error"] = res::id_invalid_payment_request_assetid;
+                    set_tx_error(result, res::id_invalid_payment_request_assetid);
                     return std::string();
                 }
                 addressee["asset_id"] = assetid_hex;
@@ -393,16 +401,16 @@ namespace sdk {
             satoshi = session.convert_amount(addressee)["satoshi"].get<amount::value_type>();
         } catch (const user_error& ex) {
             // Note the error, and create a 0 satoshi output
-            result["error"] = ex.what();
+            set_tx_error(result, ex.what());
         } catch (const std::exception&) {
             // Note the error, and create a 0 satoshi output
-            result["error"] = res::id_invalid_amount;
+            set_tx_error(result, res::id_invalid_amount);
         }
 
         // Transactions with outputs below the dust threshold (except OP_RETURN)
         // are not relayed by network nodes
         if (!result.value("send_all", false) && satoshi.value() < session.get_dust_threshold()) {
-            result["error"] = res::id_invalid_amount;
+            set_tx_error(result, res::id_invalid_amount);
         }
 
         amount::strip_non_satoshi_keys(addressee);

src/transaction_utils.hpp

@@ -73,6 +73,9 @@ namespace sdk {
     std::vector<unsigned char> scriptpubkey_from_address(
         const network_parameters& net_params, const std::string& address);
 
+    // Set the error in a transaction, if it hasn't been set already
+    void set_tx_error(nlohmann::json& result, const std::string& error);
+
     // Add an output to a tx given its address
     amount add_tx_output(const network_parameters& net_params, nlohmann::json& result, wally_tx_ptr& tx,
         const std::string& address, amount::value_type satoshi = 0, const std::string& asset_id = {});