Merge bitcoin/bitcoin#28162: refactor: Revert additional univalue check in ParseSighashString

06199a9 refactor: Revert addition of univalue sighash string check (TheCharlatan)
0b47c16 doc: Correct release-notes for sighashtype exceptions (TheCharlatan)

Pull request description:

  This is a follow up for #28113.

  The string type check is already done by the rpc parser / RPCHelpMan. Re-doing it is adding dead code. Instead, throwing an exception when the assumption does not hold is the already correct behavior. Pointed out in this [comment](https://github.com/bitcoin/bitcoin/pull/28113/files#r1274568557).

  Also correct the release note for the correct sighashtype exception change. There is no change in the handling of non-string sighashtype arugments. Pointed out in this [comment](https://github.com/bitcoin/bitcoin/pull/28113/files#r1274567555).

ACKs for top commit:
  MarcoFalke:
    lgtm ACK 06199a9
  jonatack:
    Tested ACK 06199a9
  stickies-v:
    ACK 06199a9

Tree-SHA512: 3faa6b3d2247624c0973df8d79c09fbf1f90ffb99f1be484e359b528f485c31affea45976759bd206e4c81cbb54ebba5ad0ef4127d1deacbfe2a58153fcc94ee

Author: fanquake

doc/release-notes-28113.md

@@ -2,6 +2,6 @@ RPC Wallet
 ----------
 
 - The `signrawtransactionwithkey`, `signrawtransactionwithwallet`,
-  `walletprocesspsbt` and `descriptorprocesspsbt` calls now return more
-  specific RPC_INVALID_PARAMETER instead of RPC_PARSE_ERROR if their
-  sighashtype argument is malformed or not a string.
+  `walletprocesspsbt` and `descriptorprocesspsbt` calls now return the more
+  specific RPC_INVALID_PARAMETER error instead of RPC_MISC_ERROR if their
+  sighashtype argument is malformed.

src/rpc/util.cpp

@@ -313,14 +313,16 @@ UniValue DescribeAddress(const CTxDestination& dest)
     return std::visit(DescribeAddressVisitor(), dest);
 }
 
+/**
+ * Returns a sighash value corresponding to the passed in argument.
+ *
+ * @pre The sighash argument should be string or null.
+*/
 int ParseSighashString(const UniValue& sighash)
 {
     if (sighash.isNull()) {
         return SIGHASH_DEFAULT;
     }
-    if (!sighash.isStr()) {
-        throw JSONRPCError(RPC_INVALID_PARAMETER, "sighash needs to be null or string");
-    }
     const auto result{SighashFromStr(sighash.get_str())};
     if (!result) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, util::ErrorString(result).original);

src/test/fuzz/parse_univalue.cpp

@@ -67,7 +67,7 @@ FUZZ_TARGET(parse_univalue, .init = initialize_parse_univalue)
     } catch (const std::runtime_error&) {
     }
     try {
-        (void)ParseSighashString(univalue);
+        if (univalue.isNull() || univalue.isStr()) (void)ParseSighashString(univalue);
     } catch (const UniValue&) {
     }
     try {