Make sure that handlers always return Json::objectValue.

src/ripple/rpc/impl/AccountFromString.cpp

@@ -25,6 +25,8 @@ namespace RPC {
 // --> strIdent: public key, account ID, or regular seed.
 // --> bStrict: Only allow account id or public key.
 // <-- bIndex: true if iIndex > 0 and used the index.
+//
+// Returns a Json::objectValue, containing error information if there was one.
 Json::Value accountFromString (
     Ledger::ref lrLedger,
     RippleAddress& naAccount,

src/ripple/rpc/impl/Handler.h

@@ -46,6 +46,16 @@ struct Handler
 
 const Handler* getHandler(std::string name);
 
+/** Return a Json::objectValue with a single entry. */
+template <class Value>
+Json::Value makeObjectValue (
+    Value const& value, Json::StaticString const& field = jss::message)
+{
+    Json::Value result (Json::objectValue);
+    result[field] = value;
+    return result;
+}
+
 } // RPC
 } // ripple
 

src/ripple/rpc/impl/LookupLedger.cpp

@@ -40,6 +40,11 @@ static const int LEDGER_VALIDATED = -3;
 //
 // In the absence of the "ledger_hash" or "ledger_index" parameters, the code
 // assumes that "ledger_index" has the value "current".
+//
+// Returns a Json::objectValue.  If there was an error, it will be in that
+// return value.  Otherwise, the object contains the field "validated" and
+// optionally the fields "ledger_hash", "ledger_index" and
+// "ledger_current_index", if they are defined.
 Json::Value lookupLedger (
     Json::Value const& params,
     Ledger::pointer& ledger,

src/ripple/rpc/impl/RPCHandler.cpp

@@ -140,17 +140,9 @@ Json::Value RPCHandler::doCommand (
         LoadEvent::autoptr ev = getApp().getJobQueue().getLoadEventAP(
             jtGENERIC, "cmd:" + strCommand);
         RPC::Context context {params, loadType, netOps_, infoSub_, role_};
-        Json::Value jvRaw = handler->method_(context);
-
-        // Regularize result.
-        if (jvRaw.isObject ())
-            return jvRaw;
-
-        // Probably got a string.
-        Json::Value jvResult (Json::objectValue);
-        jvResult[jss::message] = jvRaw;
-
-        return jvResult;
+        auto result = handler->method_(context);
+        assert (result.isObject());
+        return result;
     }
     catch (std::exception& e)
     {

src/ripple/rpc/impl/TransactionSign.h

@@ -100,6 +100,8 @@ public:
 
 } // namespace RPCDetail
 
+
+/** Returns a Json::objectValue. */
 Json::Value transactionSign (
     Json::Value params,
     bool bSubmit,