[ox/std] Add Result::transformError

(synced from fdf39d1a25)

src/ox/std/error.hpp

@@ -307,6 +307,13 @@ struct [[nodiscard]] Result {
 		return std::move(value);
 	}
 
+	constexpr Result transformError(ErrorCode const ec, CString const msg) && {
+		if (error) {
+			error = Error{ec, msg};
+		}
+		return *this;
+	}
+
 };
 
 namespace detail {