rpc/wallet: initialize nFeeRequired to avoid using garbage value on failure

Author: kallewoof

src/wallet/rpcwallet.cpp

@@ -343,7 +343,7 @@ static CTransactionRef SendMoney(interfaces::Chain::Lock& locked_chain, CWallet
     CScript scriptPubKey = GetScriptForDestination(address);
 
     // Create and send the transaction
-    CAmount nFeeRequired;
+    CAmount nFeeRequired = 0;
     std::string strError;
     std::vector<CRecipient> vecSend;
     int nChangePosRet = -1;