Running master 4d661ba:
```
src/bitcoin-cli combinepsbt [""] or src/bitcoin-cli combinepsbt []
```

```
  * frame #0: 0x000000010016054a bitcoind`PartiallySignedTransaction::PartiallySignedTransaction(PartiallySignedTransaction const&) [inlined] boost::optional_detail::optional_base<CMutableTransaction>::is_initialized(this=0x0000000000000000) const at optional.hpp:394 [opt]
    frame #1: 0x000000010016054a bitcoind`PartiallySignedTransaction::PartiallySignedTransaction(PartiallySignedTransaction const&) [inlined] boost::optional_detail::optional_base<CMutableTransaction>::optional_base(this=<unavailable>, rhs=0x0000000000000000) at optional.hpp:196 [opt]
    frame #2: 0x0000000100160542 bitcoind`PartiallySignedTransaction::PartiallySignedTransaction(PartiallySignedTransaction const&) [inlined] boost::optional<CMutableTransaction>::optional(this=0x000070000b9fe7c0, (null)=0x0000000000000000) at optional.hpp:958 [opt]
    frame #3: 0x0000000100160542 bitcoind`PartiallySignedTransaction::PartiallySignedTransaction(PartiallySignedTransaction const&) [inlined] boost::optional<CMutableTransaction>::optional(this=0x000070000b9fe7c0, (null)=0x0000000000000000) at optional.hpp:958 [opt]
    frame #4: 0x0000000100160542 bitcoind`PartiallySignedTransaction::PartiallySignedTransaction(this=0x000070000b9fe7c0, psbt_in=0x0000000000000000) at sign.h:576 [opt]
    frame #5: 0x0000000100142ae5 bitcoind`combinepsbt(JSONRPCRequest const&) [inlined] PartiallySignedTransaction::PartiallySignedTransaction(this=0x000070000b9fe700, psbt_in=<unavailable>) at sign.h:576 [opt]
    frame #6: 0x0000000100142ae0 bitcoind`combinepsbt(request=<unavailable>) at rawtransaction.cpp:1526 [opt]
    frame #7: 0x0000000100170f0a bitcoind`CRPCTable::execute(this=<unavailable>, request=0x000070000b9fead0) const at server.cpp:557 [opt]
```
+ HelpExampleRpc("decoderawtransaction", "\"hexstring\"")
                },
            }.ToString());
    RPCTypeCheck(request.params, {UniValue::VSTR, UniValue::VBOOL});
    CMutableTransaction mtx;
    bool try_witness = request.params[1].isNull() ? true : request.params[1].get_bool();
    bool try_no_witness = request.params[1].isNull() ? true : !request.params[1].get_bool();
    if (!DecodeHexTx(mtx, request.params[0].get_str(), try_no_witness, try_witness)) {
        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "TX decode failed");
    }
    UniValue result(UniValue::VOBJ);
    TxToUniv(CTransaction(std::move(mtx)), uint256(), result, false);
    return result;
}
static UniValue decodescript(const JSONRPCRequest& request)
{
    if (request.fHelp || request.params.size() != 1)
        throw std::runtime_error(
            RPCHelpMan{"decodescript",
                "\nDecode a hex-encoded script.\n",
                {
                    {"hexstring", RPCArg::Type::STR_HEX,  false,  "", "the hex-encoded script"},
                },
                RPCResult{
            "{\n"
            "  \"asm\":\"asm\",   (string) Script public key\n"
            "  \"hex\":\"hex\",   (string) hex-encoded public key\n"
            "  \"type\":\"type\", (string) The output type\n"
            "  \"reqSigs\": n,    (numeric) The required signatures\n"
            "  \"addresses\": [   (json array of string)\n"