fix: browseField crash, improve readability, fix shadowing

src/creatures/monsters/spawns/spawn_monster.cpp

@@ -327,7 +327,7 @@ void SpawnMonster::scheduleSpawn(uint32_t spawnMonsterId, spawnBlock_t &sb, cons
 }
 
 void SpawnMonster::cleanup() {
-	for (auto it = spawnedMonsterMap.begin(); it != spawnedMonsterMap.end(); ) {
+	for (auto it = spawnedMonsterMap.begin(); it != spawnedMonsterMap.end();) {
 		const auto &monster = it->second;
 		if (!monster || monster->isRemoved()) {
 			auto spawnIt = spawnMonsterMap.find(it->first);

src/game/game.cpp

@@ -4123,7 +4123,7 @@ void Game::playerMoveUpContainer(uint32_t playerId, uint8_t cid) {
 
 		auto it = browseFields.find(tile);
 		if (it == browseFields.end() || it->second.expired()) {
-			parentContainer = Container::create(tile);
+			parentContainer = Container::createBrowseField(tile);
 			browseFields[tile] = parentContainer;
 		} else {
 			parentContainer = it->second.lock();
@@ -4688,7 +4688,7 @@ void Game::playerBrowseField(uint32_t playerId, const Position &pos) {
 
 	auto it = browseFields.find(tile);
 	if (it == browseFields.end() || it->second.expired()) {
-		container = Container::create(tile);
+		container = Container::createBrowseField(tile);
 		browseFields[tile] = container;
 	} else {
 		container = it->second.lock();

src/items/containers/container.cpp

@@ -44,20 +44,36 @@ std::shared_ptr<Container> Container::create(uint16_t type, uint16_t size, bool
 	return std::make_shared<Container>(type, size, unlocked, pagination);
 }
 
-std::shared_ptr<Container> Container::create(const std::shared_ptr<Tile> &tile) {
-	auto container = std::make_shared<Container>(ITEM_BROWSEFIELD, 30, false, true);
+std::shared_ptr<Container> Container::createBrowseField(const std::shared_ptr<Tile> &tile) {
+	const auto &newContainer = create(ITEM_BROWSEFIELD, 30, false, true);
+	if (!newContainer || !tile) {
+		return nullptr;
+	}
+
 	const TileItemVector* itemVector = tile->getItemList();
 	if (itemVector) {
 		for (const auto &item : *itemVector) {
-			if (((item->getContainer() || item->hasProperty(CONST_PROP_MOVABLE)) || (item->isWrapable() && !item->hasProperty(CONST_PROP_MOVABLE) && !item->hasProperty(CONST_PROP_BLOCKPATH))) && !item->hasAttribute(ItemAttribute_t::UNIQUEID)) {
-				container->itemlist.push_front(item);
-				item->setParent(container);
+			if (!item) {
+				continue;
 			}
+
+			// Checks if the item has an internal container, is movable, or is packable without blocking the path.
+			bool isItemValid = item->getContainer() || item->hasProperty(CONST_PROP_MOVABLE) || (item->isWrapable() && !item->hasProperty(CONST_PROP_MOVABLE) && !item->hasProperty(CONST_PROP_BLOCKPATH));
+
+			// If the item has a unique ID or is not valid, skip to the next item.
+			if (item->hasAttribute(ItemAttribute_t::UNIQUEID) || !isItemValid) {
+				continue;
+			}
+
+			// Add the item to the new container and set its parent.
+			newContainer->itemlist.push_front(item);
+			item->setParent(newContainer);
 		}
 	}
 
-	container->setParent(tile);
-	return container;
+	// Set the parent of the new container to be the tile.
+	newContainer->setParent(tile);
+	return newContainer;
 }
 
 Container::~Container() {

src/items/containers/container.hpp

@@ -138,7 +138,21 @@ class Container : public Item, public Cylinder {
 
 	static std::shared_ptr<Container> create(uint16_t type);
 	static std::shared_ptr<Container> create(uint16_t type, uint16_t size, bool unlocked = true, bool pagination = false);
-	static std::shared_ptr<Container> create(const std::shared_ptr<Tile> &type);
+
+	/**
+	 * @brief Creates a container for browse field functionality with items from a specified tile.
+	 *
+	 * This function generates a new container specifically for browse field use,
+	 * populating it with items that meet certain criteria from the provided tile. Items
+	 * that can be included must either have an internal container, be movable, or be
+	 * wrapable without blocking path and without a unique ID.
+	 *
+	 * @param tile A shared pointer to the Tile from which items will be sourced.
+	 * @return std::shared_ptr<Container> Returns a shared pointer to the newly created Container if successful; otherwise, returns nullptr.
+	 *
+	 * @note This function will return nullptr if the newContainer could not be created or if the tile pointer is null.
+	 */
+	static std::shared_ptr<Container> createBrowseField(const std::shared_ptr<Tile> &type);
 
 	// non-copyable
 	Container(const Container &) = delete;

src/server/network/protocol/protocolgame.cpp

@@ -4615,7 +4615,7 @@ void ProtocolGame::sendUnjustifiedPoints(const uint8_t &dayProgress, const uint8
 }
 
 void ProtocolGame::sendContainer(uint8_t cid, const std::shared_ptr<Container> &container, bool hasParent, uint16_t firstIndex) {
-	if (!player) {
+	if (!player || !container) {
 		return;
 	}