Steps to reproduce on regtest:

```
converttopsbt 02000000000101ab73dba46508bacdb49a988ddd74bc9d39c9cb7e057af060ca8c6b6861e28e3c0300000000feffffff02b828d0b20000000017a914d1954862afd728fbb055149002958e1d1b9e1f0b8700ca9a3b0000000017a91442170ccb3441cff1723af9afab6f2553103e1d578702473044022077380c6e16496d9905aef120694c329be51522847cb5d53fa74b94698c95678d02202d32c46e0e17420a83dee830fefda7d40529182f5d82be47c2b49a7b83214ab50121026d483d6628dcc3ef6e3ab9ed4937c452c263c7e0ac80eb4be97426d5da8f640500000000
```
or 
```
converttopsbt 02000000000101ab73dba46508bacdb49a988ddd74bc9d39c9cb7e057af060ca8c6b6861e28e3c0300000000feffffff02b828d0b20000000017a914d1954862afd728fbb055149002958e1d1b9e1f0b8700ca9a3b0000000017a91442170ccb3441cff1723af9afab6f2553103e1d578702473044022077380c6e16496d9905aef120694c329be51522847cb5d53fa74b94698c95678d02202d32c46e0e17420a83dee830fefda7d40529182f5d82be47c2b49a7b83214ab50121026d483d6628dcc3ef6e3ab9ed4937c452c263c7e0ac80eb4be97426d5da8f640500000000 false
```

Further reading: #13738
{
    if (request.fHelp || request.params.size() != 1)
        throw std::runtime_error(
            RPCHelpMan{"combinerawtransaction",
                "\nCombine multiple partially signed transactions into one transaction.\n"
                "The combined transaction may be another partially signed transaction or a \n"
                "fully signed transaction.",
                {
                    {"txs", RPCArg::Type::ARR, RPCArg::Optional::NO, "A json array of hex strings of partially signed transactions",
                        {
                            {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A transaction hash"},
                        },
                        },
                },
                RPCResult{
            "\"hex\"            (string) The hex-encoded raw transaction with signature(s)\n"
                },
                RPCExamples{
                    HelpExampleCli("combinerawtransaction", "[\"myhex1\", \"myhex2\", \"myhex3\"]")
                },
            }.ToString());
    UniValue txs = request.params[0].get_array();
    std::vector<CMutableTransaction> txVariants(txs.size());
    for (unsigned int idx = 0; idx < txs.size(); idx++) {
        if (!DecodeHexTx(txVariants[idx], txs[idx].get_str(), true)) {
            throw JSONRPCError(RPC_DESERIALIZATION_ERROR, strprintf("TX decode failed for tx %d", idx));
        }
    }
    if (txVariants.empty()) {