rpc: treat univalue type check error as RPC_TYPE_ERROR, not RPC_MISC_ERROR

By throwing a custom exception from `Univalue::checkType` (instead of a plain
std::runtime_error) and catching it on the RPC server request handler.

So we properly return RPC_TYPE_ERROR (-3) on arg type errors and
not the general RPC_MISC_ERROR (-1).

2 files changed, 6 insertions, 1 deletions

diff --git a/src/univalue/include/univalue.h b/src/univalue/include/univalue.h
index ccaf56a271..850d0a1cbc 100644
--- a/src/univalue/include/univalue.h
+++ b/src/univalue/include/univalue.h
@@ -19,6 +19,11 @@ class UniValue {
 public:
     enum VType { VNULL, VOBJ, VARR, VSTR, VNUM, VBOOL, };
 
+    class type_error : public std::runtime_error
+    {
+        using std::runtime_error::runtime_error;
+    };
+
     UniValue() { typ = VNULL; }
     UniValue(UniValue::VType initialType, const std::string& initialStr = "") {
         typ = initialType;
diff --git a/src/univalue/lib/univalue.cpp b/src/univalue/lib/univalue.cpp
index 12a434dd0e..4448981d3e 100644
--- a/src/univalue/lib/univalue.cpp
+++ b/src/univalue/lib/univalue.cpp
@@ -210,7 +210,7 @@ const UniValue& UniValue::operator[](size_t index) const
 void UniValue::checkType(const VType& expected) const
 {
     if (typ != expected) {
-        throw std::runtime_error{"JSON value of type " + std::string{uvTypeName(typ)} + " is not of expected type " +
+        throw type_error{"JSON value of type " + std::string{uvTypeName(typ)} + " is not of expected type " +
                                  std::string{uvTypeName(expected)}};
     }
 }