Fix position of version argument in walletcreatefundedpsbt (#1474)

* fix position of version argument and add test

* add test for version number

---------

Co-authored-by: Tom Trevethan <ttrevethan@blockstream.com>

Author: tomt1664

src/wallet/rpc/spend.cpp

@@ -1540,7 +1540,6 @@ RPCHelpMan walletcreatefundedpsbt()
         UniValue::VNUM,
         UniValue::VOBJ,
         UniValue::VBOOL,
-        UniValue::VOBJ,
         UniValue::VNUM,
         }, true
     );
@@ -1564,7 +1563,7 @@ RPCHelpMan walletcreatefundedpsbt()
     // Make a blank psbt
     uint32_t psbt_version = 2;
     if (!request.params[5].isNull()) {
-        psbt_version = request.params[6].get_int();
+        psbt_version = request.params[5].get_int();
     }
     if (psbt_version != 2) {
         throw JSONRPCError(RPC_INVALID_PARAMETER, "The PSBT version can only be 2");

test/functional/rpc_psbt.py

@@ -1149,6 +1149,8 @@ def test_psbt_input_keys(psbt_input, keys):
         # An external input without solving data should result in an error
         assert_raises_rpc_error(-4, "Insufficient funds", wallet.walletcreatefundedpsbt, [ext_utxo], [{self.nodes[0].getnewaddress(): 15}])
 
+        # ELEMENTS: check psbt version is 2
+        assert_raises_rpc_error(-8, "The PSBT version can only be 2", wallet.walletcreatefundedpsbt, [ext_utxo], [{self.nodes[0].getnewaddress(): 15}], 0, {"add_inputs": True, "solving_data": {"pubkeys": [addr_info['pubkey']], "scripts": [addr_info["embedded"]["scriptPubKey"]]}},True,1)
         # But funding should work when the solving data is provided
         psbt = wallet.walletcreatefundedpsbt([ext_utxo], [{self.nodes[0].getnewaddress(): 15}], 0, {"add_inputs": True, "solving_data": {"pubkeys": [addr_info['pubkey']], "scripts": [addr_info["embedded"]["scriptPubKey"]]}})
         signed = wallet.walletprocesspsbt(psbt['psbt'])