refactor: Avoid implicit-integer-sign-change in createTransaction

src/wallet/interfaces.cpp

@@ -286,7 +286,7 @@ public:
         if (!res) return util::Error{util::ErrorString(res)};
         const auto& txr = *res;
         fee = txr.fee;
-        change_pos = txr.change_pos ? *txr.change_pos : -1;
+        change_pos = txr.change_pos ? int(*txr.change_pos) : -1;
 
         return txr.tx;
     }