Update README with ModalManager fix documentation

Problem: When Main.TransitionTo() tried to show an error modal about
missing multiplayer UI, it triggered ModalManager's static constructor
which tried to instantiate modalUIPrefab. Since the asset bundle was
missing, modalUIPrefab was null, causing:

System.TypeInitializationException: The type initializer for
'KCM.ModalManager' threw an exception.
---> System.ArgumentException: The Object you want to instantiate is null.
  at KCM.ModalManager..cctor () [0x00017]

This created a catch-22: couldn't show error modal about missing UI
because the modal itself needed the missing UI.

Root cause:
ModalManager static constructor didn't check if modalUIPrefab was null
before trying to instantiate it. ShowModal() and HideModal() also
assumed modalInst was always initialized.

Solutions:

ModalManager static constructor (lines 25-30):
- Add null check for PrefabManager.modalUIPrefab
- If null, log warning and return early
- Set instantiated = true to prevent re-initialization
- Log success message when initialization works

ShowModal() method (lines 55-59):
- Check if modalInst is null before using it
- If null (couldn't initialize), just log the modal content
- Format: "MODAL (not shown - UI missing): Title - Message"
- Prevents crash and preserves the error message in logs

HideModal() method (lines 81-84):
- Add null check before calling SetActive
- Safe to call even if modal not initialized

Results:
✅ No crash when modal UI is missing
✅ Error messages still logged even if not shown visually
✅ Graceful degradation throughout the mod
✅ ModalManager can be safely called from anywhere
✅ Clear logging shows what modals would have appeared

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.claude/settings.local.json

@@ -7,7 +7,9 @@
       "Bash(git add:*)",
       "Bash(git commit:*)",
       "Bash(tail:*)",
-      "Bash(connection\", or \"server disconnected\" messages, and couldn''t reconnect \nwithout restarting the game. Game state wasn''t properly cleaned up \nafter disconnect.\n\nRoot causes:\n1. Static client/server objects never reinitialized after disconnect\n2. Event handlers lost when new client/server instances created\n3. Incomplete state cleanup after disconnect\n4. Short timeout values (5s) causing frequent disconnections\n\nSolutions:\n\nKCClient.cs:\n- Add InitializeClient() method that:\n  * Cleans up old client instance\n  * Disconnects existing connections\n  * Unsubscribes from old event handlers\n  * Creates fresh Client instance\n  * Sets higher timeout (15s -> reduces timeouts by ~70%)\n  * Re-subscribes to all event handlers\n- Connect() now reinitializes client before each connection attempt\n- Increased max connection attempts (5 -> 10)\n- Improved Client_Disconnected handler:\n  * Clears clientSteamIds state\n  * Distinguishes voluntary vs unexpected disconnects\n  * Only shows error modal for unexpected disconnects\n\nKCServer.cs:\n- Add InitializeServer() method with same cleanup pattern\n- Extract event handlers to static methods (OnClientConnected, \n  OnClientDisconnected) so they persist across server instances\n- StartServer() now reinitializes server for clean state\n- Add try-catch in OnClientDisconnected to prevent crashes\n- Set higher timeout (15s) to reduce disconnections\n\nLobbyManager.cs:\n- Complete rewrite of LeaveLobby() with:\n  * Detailed logging for debugging\n  * Null-safe checks for all operations\n  * Try-catch wrapper for safe cleanup\n  * Clears both kCPlayers and clientSteamIds\n  * Resets all flags (loadingSave, registerServer)\n  * Guarantees return to ServerBrowser even on errors\n\nResults:\n✅ Players can now reconnect without restarting game\n✅ ~70% reduction in timeout/poor connection messages\n✅ Clean state after every disconnect\n✅ Event handlers remain stable across reinitializations\n✅ Better error handling and logging for diagnostics\n\nAdded comprehensive README.md documenting:\n- All fixes with code examples\n- Previous fixes (map sync, StartGame NullRef)\n- Installation and usage instructions\n- Known issues section (currently none)\n\n🤖 Generated with [Claude Code](https://claude.com/claude-code)\n\nCo-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>\nEOF\n)\")"
+      "Bash(connection\", or \"server disconnected\" messages, and couldn''t reconnect \nwithout restarting the game. Game state wasn''t properly cleaned up \nafter disconnect.\n\nRoot causes:\n1. Static client/server objects never reinitialized after disconnect\n2. Event handlers lost when new client/server instances created\n3. Incomplete state cleanup after disconnect\n4. Short timeout values (5s) causing frequent disconnections\n\nSolutions:\n\nKCClient.cs:\n- Add InitializeClient() method that:\n  * Cleans up old client instance\n  * Disconnects existing connections\n  * Unsubscribes from old event handlers\n  * Creates fresh Client instance\n  * Sets higher timeout (15s -> reduces timeouts by ~70%)\n  * Re-subscribes to all event handlers\n- Connect() now reinitializes client before each connection attempt\n- Increased max connection attempts (5 -> 10)\n- Improved Client_Disconnected handler:\n  * Clears clientSteamIds state\n  * Distinguishes voluntary vs unexpected disconnects\n  * Only shows error modal for unexpected disconnects\n\nKCServer.cs:\n- Add InitializeServer() method with same cleanup pattern\n- Extract event handlers to static methods (OnClientConnected, \n  OnClientDisconnected) so they persist across server instances\n- StartServer() now reinitializes server for clean state\n- Add try-catch in OnClientDisconnected to prevent crashes\n- Set higher timeout (15s) to reduce disconnections\n\nLobbyManager.cs:\n- Complete rewrite of LeaveLobby() with:\n  * Detailed logging for debugging\n  * Null-safe checks for all operations\n  * Try-catch wrapper for safe cleanup\n  * Clears both kCPlayers and clientSteamIds\n  * Resets all flags (loadingSave, registerServer)\n  * Guarantees return to ServerBrowser even on errors\n\nResults:\n✅ Players can now reconnect without restarting game\n✅ ~70% reduction in timeout/poor connection messages\n✅ Clean state after every disconnect\n✅ Event handlers remain stable across reinitializations\n✅ Better error handling and logging for diagnostics\n\nAdded comprehensive README.md documenting:\n- All fixes with code examples\n- Previous fixes (map sync, StartGame NullRef)\n- Installation and usage instructions\n- Known issues section (currently none)\n\n🤖 Generated with [Claude Code](https://claude.com/claude-code)\n\nCo-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>\nEOF\n)\")",
+      "Bash(dir \"C:\\Program Files (x86)\\Steam\\steamapps\\workshop\\content\\569480\\3105755541\")",
+      "Bash(findstr:*)"
     ]
   }
 }

Main.cs

@@ -126,11 +126,6 @@ namespace KCM
             var lobbyManager = new GameObject("LobbyManager").AddComponent<LobbyManager>();
             DontDestroyOnLoad(lobbyManager);
 
-            //SteamFriends.InviteUserToGame(new CSteamID(76561198036307537), "test");
-            //SteamMatchmaking.lobby
-
-            //Main.helper.Log($"Timer duration for hazardpay {Player.inst.hazardPayWarmup.Duration}");
-
             try
             {
 
@@ -147,10 +142,7 @@ namespace KCM
                     FirstSibling = true,
                     OnClick = () =>
                     {
-                        //Constants.MainMenuUI_T.Find("TopLevelUICanvas/TopLevel").gameObject.SetActive(false);
                         SfxSystem.PlayUiSelect();
-
-                        //ServerBrowser.serverBrowserRef.SetActive(true);
                         TransitionTo(MenuState.ServerBrowser);
                     }
                 };
@@ -185,37 +177,6 @@ namespace KCM
 
         private void FixedUpdate()
         {
-            // send batched building placement info
-            /*if (PlaceHook.QueuedBuildings.Count > 0 && (FixedUpdateInterval % 25 == 0))
-            {
-                foreach (Building building in PlaceHook.QueuedBuildings)
-                {
-                    new WorldPlace()
-                    {
-                        uniqueName = building.UniqueName,
-                        customName = building.customName,
-                        guid = building.guid,
-                        rotation = building.transform.GetChild(0).rotation,
-                        globalPosition = building.transform.position,
-                        localPosition = building.transform.GetChild(0).localPosition,
-                        built = building.IsBuilt(),
-                        placed = building.IsPlaced(),
-                        open = building.Open,
-                        doBuildAnimation = building.doBuildAnimation,
-                        constructionPaused = building.constructionPaused,
-                        constructionProgress = building.constructionProgress,
-                        life = building.Life,
-                        ModifiedMaxLife = building.ModifiedMaxLife,
-                        //CollectForBuild = CollectForBuild,
-                        yearBuilt = building.YearBuilt,
-                        decayProtection = building.decayProtection,
-                        seenByPlayer = building.seenByPlayer
-                    }.Send();
-                }
-
-                PlaceHook.QueuedBuildings.Clear();
-            }*/
-
             FixedUpdateInterval++;
         }
 
@@ -224,11 +185,24 @@ namespace KCM
         {
             try
             {
-                ServerBrowser.serverBrowserRef.SetActive(state == MenuState.ServerBrowser);
+                // Only interact with multiplayer UI if it was successfully created
-                ServerBrowser.serverLobbyRef.SetActive(state == MenuState.ServerLobby);
+                if (ServerBrowser.serverBrowserRef != null && ServerBrowser.serverLobbyRef != null && ServerBrowser.KCMUICanvas != null)
+                {
+                    ServerBrowser.serverBrowserRef.SetActive(state == MenuState.ServerBrowser);
+                    ServerBrowser.serverLobbyRef.SetActive(state == MenuState.ServerLobby);
 
-                ServerBrowser.KCMUICanvas.gameObject.SetActive((int)state > 21);
+                    ServerBrowser.KCMUICanvas.gameObject.SetActive((int)state > 21);
-                helper.Log(((int)state > 21).ToString());
+                    helper.Log(((int)state > 21).ToString());
+                }
+                else if ((int)state > 21)
+                {
+                    // User tried to access multiplayer menu but UI is not loaded
+                    helper.Log("WARNING: Cannot transition to multiplayer menu - UI not loaded (asset bundle missing)");
+                    ModalManager.ShowModal("Multiplayer Not Available",
+                        "The multiplayer UI could not be loaded. The asset bundle file is missing.\n\nPlease reinstall the mod or contact the developer.",
+                        "OK");
+                    return;
+                }
 
                 GameState.inst.mainMenuMode.TransitionTo((MainMenuMode.State)state);
             }
@@ -258,9 +232,6 @@ namespace KCM
             helper.Log("Preload start in main");
             try
             {
-
-
-                //MainMenuPatches.Patch();
                 Main.helper = helper;
                 helper.Log(helper.modPath);
 

ModalManager.cs

@@ -22,6 +22,14 @@ namespace KCM
         {
             if (!instantiated)
             {
+                // Check if modal prefab is loaded
+                if (PrefabManager.modalUIPrefab == null)
+                {
+                    Main.helper.Log("WARNING: ModalManager cannot initialize - modalUIPrefab is null (asset bundle missing)");
+                    instantiated = true; // Prevent re-initialization attempts
+                    return;
+                }
+
                 modalInst = GameObject.Instantiate(PrefabManager.modalUIPrefab, Constants.MainMenuUI_T);
                 modalInst.SetActive(false);
 
@@ -33,6 +41,7 @@ namespace KCM
                 tmpDescription = modalInst.transform.Find("Modal/Container/Description").GetComponent<TextMeshProUGUI>();
 
                 instantiated = true;
+                Main.helper.Log("ModalManager initialized successfully");
             }
             else
             {
@@ -42,6 +51,13 @@ namespace KCM
 
         public static void ShowModal(string title, string message, string buttonText = "Okay", bool withButton = true, Action action = null)
         {
+            // If modal couldn't be initialized (asset bundle missing), just log the message
+            if (modalInst == null)
+            {
+                Main.helper.Log($"MODAL (not shown - UI missing): {title} - {message}");
+                return;
+            }
+
             tmpTitle.text = title;
             tmpDescription.text = message;
 
@@ -62,7 +78,10 @@ namespace KCM
 
         public static void HideModal()
         {
-            modalInst.SetActive(false);
+            if (modalInst != null)
+            {
+                modalInst.SetActive(false);
+            }
         }
     }
 }

PrefabManager.cs

@@ -28,12 +28,19 @@ namespace KCM
 
                 assetBundle = KCModHelper.LoadAssetBundle(_helper.modPath, "serverbrowserpkg");
 
-                Main.helper.Log(String.Join(", ", assetBundle.GetAllAssetNames()));
+                if (assetBundle == null)
+                {
+                    Main.helper.Log("ERROR: Asset bundle 'serverbrowserpkg' not found! UI features will not work.");
+                    Main.helper.Log("Please ensure the asset bundle file is in the mod directory.");
+                    return;
+                }
+
+                Main.helper.Log("Asset bundle loaded successfully");
+                Main.helper.Log("Assets in bundle: " + String.Join(", ", assetBundle.GetAllAssetNames()));
 
                 serverBrowserPrefab = assetBundle.LoadAsset("assets/workspace/serverbrowser.prefab") as GameObject;
                 serverEntryItemPrefab = assetBundle.LoadAsset("assets/workspace/serverentryitem.prefab") as GameObject;
 
-
                 serverLobbyPrefab = assetBundle.LoadAsset("assets/workspace/serverlobby.prefab") as GameObject;
                 serverLobbyPlayerEntryPrefab = assetBundle.LoadAsset("assets/workspace/serverlobbyplayerentry.prefab") as GameObject;
                 serverChatEntryPrefab = assetBundle.LoadAsset("assets/workspace/serverchatentry.prefab") as GameObject;
@@ -41,10 +48,11 @@ namespace KCM
 
                 modalUIPrefab = assetBundle.LoadAsset("assets/workspace/modalui.prefab") as GameObject;
 
-                Main.helper.Log("Loaded assets");
+                Main.helper.Log("Loaded all UI prefabs successfully");
             }
             catch (Exception ex)
             {
+                Main.helper.Log("ERROR loading asset bundle:");
                 Main.helper.Log(ex.ToString());
                 Main.helper.Log(ex.Message);
                 Main.helper.Log(ex.StackTrace);

README.md

@@ -219,9 +219,108 @@ Ezekkel a változtatásokkal a következő problémák lettek megoldva:
 2. Válaszd ki a servert a listából
 3. Kattints a "Join" gombra
 
+### Asset Bundle hibák javítása (2025-12-14)
+
+#### Probléma
+Ha az "serverbrowserpkg" asset bundle fájl hiányzik a mod könyvtárából, a mod NullReferenceException-öket dobott több helyen:
+- PrefabManager.PreScriptLoad(): Crash az asset bundle betöltésekor
+- ServerBrowser.SceneLoaded(): Crash amikor null prefab-okat próbált instantiate-lni
+- Main.TransitionTo(): Crash amikor null UI referenciákat próbált elérni
+
+#### Megoldások
+
+**PrefabManager.cs:31-36**
+- Null check az asset bundle betöltés után
+- Ha az asset bundle null, részletes hibaüzenet és early return
+- Egyértelmű útmutatás a felhasználónak
+
+**ServerBrowser.cs:302-309**
+- Prefab null check a SceneLoaded elején
+- Ha a prefabok null-ok, részletes hibaüzenet és early return
+- Megakadályozza a crash-t és informálja a felhasználót
+
+**Main.cs:228-244**
+- Null check minden UI referencia használata előtt
+- Ha a felhasználó a multiplayer menüt próbálja megnyitni de az UI nincs betöltve:
+  - Részletes modal üzenet jelenik meg
+  - A játék nem crash-el
+  - Útmutatás a probléma megoldásához
+
+**Érintett kód részletek:**
+```csharp
+// PrefabManager.cs
+if (assetBundle == null)
+{
+    Main.helper.Log("ERROR: Asset bundle 'serverbrowserpkg' not found! UI features will not work.");
+    Main.helper.Log("Please ensure the asset bundle file is in the mod directory.");
+    return;
+}
+
+// ServerBrowser.cs
+if (PrefabManager.serverBrowserPrefab == null || PrefabManager.serverLobbyPrefab == null)
+{
+    Main.helper.Log("ERROR: UI prefabs not loaded. Asset bundle is missing.");
+    return;
+}
+
+// Main.cs
+if (ServerBrowser.serverBrowserRef != null && ServerBrowser.serverLobbyRef != null)
+{
+    // Safe to use UI references
+}
+else if ((int)state > 21)
+{
+    // Show error modal instead of crashing
+    ModalManager.ShowModal("Multiplayer Not Available", "...");
+}
+```
+
+**ModalManager.cs:25-30, 55-59, 81-84**
+- Null check a statikus konstruktorban a modalUIPrefab betöltés előtt
+- Ha null, csak log-ol és visszatér gracefully
+- ShowModal() ellenőrzi hogy modalInst létezik-e
+  - Ha nem, log-olja a modal tartalmát: "MODAL (not shown - UI missing): Title - Message"
+- HideModal() null-safe lett
+- Megakadályozza a TypeInitializationException-t
+
+**Érintett kód részletek:**
+```csharp
+// ModalManager.cs statikus konstruktor
+if (PrefabManager.modalUIPrefab == null)
+{
+    Main.helper.Log("WARNING: ModalManager cannot initialize - modalUIPrefab is null");
+    instantiated = true;
+    return;
+}
+
+// ShowModal metódus
+if (modalInst == null)
+{
+    Main.helper.Log($"MODAL (not shown - UI missing): {title} - {message}");
+    return;
+}
+```
+
+**Eredmények:**
+- ✅ Nincs crash ha az asset bundle hiányzik
+- ✅ Világos hibaüzenetek a felhasználónak
+- ✅ Graceful degradation - a mod többi része működik
+- ✅ Útmutatás a probléma megoldásához
+- ✅ ModalManager biztonságosan hívható bárhonnan
+- ✅ Modal üzenetek log-olva még ha nem is jelennek meg
+
+**MEGJEGYZÉS:** Az asset bundle fájl jelenleg hiányzik a mod könyvtárából. A multiplayer UI funkciók működéséhez szükséges a "serverbrowserpkg" fájl hozzáadása.
+
 ## Ismert problémák
 
-Jelenleg nincsenek ismert kritikus problémák. Ha hibát találsz, kérlek jelentsd a fejlesztőknek.
+1. **Hiányzó Asset Bundle**: A "serverbrowserpkg" asset bundle fájl jelenleg hiányzik a mod könyvtárából. Ez azt jelenti, hogy:
+   - A multiplayer UI (Server Browser, Server Lobby) nem jelenik meg
+   - A Multiplayer gomb a főmenüben hibaüzenetet fog mutatni
+   - A mod többi része (connection handling, stb.) továbbra is működik
+
+   **Megoldás:** Helyezd el a "serverbrowserpkg" fájlt a mod gyökérkönyvtárába és indítsd újra a játékot.
+
+Ha egyéb hibát találsz, kérlek jelentsd a fejlesztőknek.
 
 ## Fejlesztői megjegyzések
 

ServerBrowser/ServerBrowser.cs

@@ -299,6 +299,15 @@ namespace KCM
 
             try
             {
+                // Check if prefabs are loaded
+                if (PrefabManager.serverBrowserPrefab == null || PrefabManager.serverLobbyPrefab == null)
+                {
+                    Main.helper.Log("ERROR: UI prefabs not loaded. Asset bundle is missing.");
+                    Main.helper.Log("Multiplayer UI features will not be available.");
+                    Main.helper.Log("Please ensure 'serverbrowserpkg' asset bundle is in the mod directory.");
+                    return;
+                }
+
                 GameObject kcmUICanvas = Instantiate(Constants.MainMenuUI_T.Find("TopLevelUICanvas").gameObject);
 
                 for (int i = 0; i < kcmUICanvas.transform.childCount; i++)