refactor: convert maybe_error into generic Result template class

src/Makefile.am

@@ -328,6 +328,7 @@ BITCOIN_CORE_H = \
   util/overflow.h \
   util/ranges.h \
   util/readwritefile.h \
+  util/result.h \
   util/underlying.h \
   util/serfloat.h \
   util/settings.h \

src/util/result.h

@@ -0,0 +1,69 @@
+// Copyright (c) 2023 The Dash Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTIL_RESULT_H
+#define BITCOIN_UTIL_RESULT_H
+
+#include <cassert>
+#include <utility> // for std::move()
+#include <variant>
+
+template<typename T>
+struct Ok {
+    constexpr explicit Ok(T val) : val_(std::move(val)) {}
+    const T val_;
+};
+
+// Specialization of the Ok struct for void type
+template<>
+struct Ok<void> {
+    constexpr Ok() = default;
+};
+
+template<typename E>
+struct Err {
+    constexpr explicit Err(E val) : val_(std::move(val)) {}
+
+    template<typename... Ts>
+    constexpr explicit Err(Ts...t) : val_{t...} {}
+
+    const E val_;
+};
+
+template<typename T, typename E>
+class Result {
+public:
+    constexpr Result(Ok<T> val) : result{val} {}
+    template<typename... Ts>
+    constexpr Result(Ts... t) : result{Ok<T>{t...}} {}
+    constexpr Result(Err<E> err) : result{err.val_} {}
+
+    [[nodiscard]] constexpr bool is_ok() const { return std::holds_alternative<Ok<T>>(result); }
+    [[nodiscard]] constexpr bool is_err() const { return !is_ok(); }
+
+    [[nodiscard]] constexpr explicit operator bool() const {
+        return is_ok();
+    }
+
+    template<typename U = T>
+    [[nodiscard]] constexpr const U& operator*() const {
+        return unwrap();
+    }
+
+    template<typename U = T>
+    [[nodiscard]] constexpr const U& unwrap() const {
+        assert(is_ok());
+        return std::get<Ok<U>>(result).val_;
+    }
+
+    [[nodiscard]] constexpr const E& err() const {
+        assert(is_err());
+        return std::get<E>(result);
+    }
+
+private:
+    std::variant<Ok<T>, E> result;
+};
+
+#endif