Merge bitcoin#25551: refactor: Throw exception on invalid Univalue pushes over silent ignore

fa277cd univalue: Throw exception on invalid pushes over silent ignore (MacroFake)
ccccc17 refactor: Default options in walletcreatefundedpsbt to VOBJ instead of VNULL (MacroFake)

Pull request description:

  The return value of the `push*` helpers is never used, but important to determine if the operation was successful. One way to fix this would be to add the "nodiscard" attribute. However, this would make the code (and this diff) overly verbose for no reason.

  So fix it by removing the never used return value. Also, fail verbosely in case of a programming mistake.

ACKs for top commit:
  furszy:
    code ACK fa277cd

Tree-SHA512: ef212a5bf5ae6bbad20acc4dafa3715521e81544185988d1eab724f440e4864a27e686aff51d5bc51b3017892c2eb8e577bcb8f37e8ddbaa0d8833bb622f2f9c

Author: fanquake

src/wallet/rpc/spend.cpp

@@ -1171,7 +1171,7 @@ RPCHelpMan walletcreatefundedpsbt()
     // the user could have gotten from another RPC command prior to now
     wallet.BlockUntilSyncedToCurrentChain();
 
-    UniValue options = request.params[3];
+    UniValue options{request.params[3].isNull() ? UniValue::VOBJ : request.params[3]};
 
     CAmount fee;
     int change_position;