fix: fix module's function serialization

Refs: #23

furvm/include/furvm/handle.hpp

@@ -308,6 +308,17 @@ public:
         delete it->second;
         m_pairs.erase(it);
     }
+
+    /**
+     * @brief Checks whether a handle exists inside.
+     *
+     * @param id Identifier of the handle.
+     * @return true if the handle exists insdie of this container.
+     */
+    template <typename IdFwd>
+    constexpr bool contains(IdFwd&& id) const {
+        return m_pairs.find(std::forward<IdFwd>(id)) != m_pairs.end();
+    }
 private:
     std::unordered_map<id_type, pair_type*> m_pairs;
 };
@@ -395,6 +406,14 @@ public:
         delete m_pairs[id];
         m_pairs[id] = nullptr;
     }
+
+    /**
+     * @brief Checks whether a handle exists inside.
+     *
+     * @param id Identifier of the handle.
+     * @return true if the handle exists insdie of this container.
+     */
+    constexpr bool contains(id_type id) const { return id < m_pairs.size() && m_pairs[id] != nullptr; }
 public:
     auto begin() { return m_pairs.begin(); }
     auto begin() const { return m_pairs.begin(); }

furvm/src/module.cpp

@@ -12,8 +12,14 @@ std::ostream& mod::serialize(std::ostream& os) const {
     detail::serialize(os, std::uint32_t(0)); // version
 
     detail::serialize(os, function_id(m_functionMap.size()));
-    for (auto* pair : m_functions) {
-        function_h func     = { pair };
+    for (function_id id = 0; id < m_functions.cend() - m_functions.cbegin(); ++id) {
+        if (!m_functions.contains(id)) {
+            detail::serialize(os, "");
+            detail::serialize(os, std::uint8_t(0xFF)); // null function
+            continue;
+        }
+
+        function_h func     = m_functions.at(id);
         bool       isPublic = m_publicFunctions.find(func->name()) != m_publicFunctions.end();
         detail::serialize(os, isPublic ? func->name() : ""); // private functions have empty names
         detail::serialize(os, std::uint8_t(func->type()));