Don't allow loading saves with maps that aren't installed

Mapify/Locale.cs

@@ -13,6 +13,7 @@ public static class Locale
         private const string DEFAULT_LANGUAGE = "English";
         public const string SESSION__MAP_SELECTOR = "mapify/session/map_selector";
         public const string LAUNCHER__SESSION_MAP = "mapify/launcher/session_map";
+        public const string LAUNCHER__SESSION_MAP_NOT_INSTALLED = "mapify/launcher/session_map_not_installed";
         public const string LOADING__PLEASE_WAIT = "mapify/loading/please_wait";
         public const string LOADING__LOADING_MAP = "mapify/loading/loading_map";
         private static readonly char[] PREFIX_CHARS = PREFIX.ToCharArray();

Mapify/Patches/AScenarioProviderPatch.cs

@@ -0,0 +1,23 @@
+using System.Linq;
+using DV.Common;
+using DV.UI;
+using HarmonyLib;
+using Mapify.Editor;
+using Mapify.Map;
+using Mapify.Utils;
+
+namespace Mapify.Patches
+{
+    [HarmonyPatch(typeof(AScenarioProvider), nameof(AScenarioProvider.CanStartNewSession))]
+    public static class AScenarioProvider_CanStartNewSession_Patch
+    {
+        private static bool Prefix(IGameSession session, ref (bool canRun, string reasonLocKey) __result)
+        {
+            BasicMapInfo basicMapInfo = session.GameData.GetBasicMapInfo();
+            if (Maps.AllMapNames.Contains(basicMapInfo.mapName))
+                return true;
+            __result = (false, Locale.LAUNCHER__SESSION_MAP_NOT_INSTALLED);
+            return false;
+        }
+    }
+}

Mapify/Patches/LauncherControllerPatch.cs

@@ -1,10 +1,14 @@
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Reflection;
 using DV.Common;
 using DV.UI;
 using DV.UI.PresetEditors;
+using DV.UIFramework;
 using HarmonyLib;
+using Mapify.Editor;
+using Mapify.Map;
 using Mapify.Utils;
 
 namespace Mapify.Patches
@@ -41,4 +45,30 @@ private static void Postfix(UIStartGameData data, ref string __result)
             __result = string.Join("\n", strings);
         }
     }
+
+    [HarmonyPatch(typeof(LauncherController), "OnRunClicked")]
+    public static class LauncherController_OnRunClicked_Patch
+    {
+        private static bool Prefix(LauncherController __instance, ISaveGame ___saveGame)
+        {
+            BasicMapInfo basicMapInfo = ___saveGame.Data.GetBasicMapInfo();
+            if (Maps.AllMapNames.Contains(basicMapInfo.mapName))
+                return true;
+
+            PopupManager popupManager = null;
+            __instance.FindPopupManager(ref popupManager);
+
+            if (!popupManager.CanShowPopup())
+            {
+                Mapify.LogError("Cannot show popup!");
+                return false;
+            }
+
+            Popup okPopupPrefab = __instance.GetComponentInParent<InitialScreenController>().continueLoadNewController.career.okPopupPrefab;
+
+            Popup popup = popupManager.ShowPopup(okPopupPrefab);
+            popup.labelTMPro.text = Locale.Get(Locale.LAUNCHER__SESSION_MAP_NOT_INSTALLED, basicMapInfo.mapName);
+            return false;
+        }
+    }
 }

locale.csv

@@ -5,3 +5,4 @@ session/map_selector__tooltip,,Select a Map
 launcher/map_selector__tooltip_disabled,,
 loading/please_wait,,"loading{0}, please wait... {1}%"
 loading/loading_map,,Loading map {0}
+launcher/session_map_not_installed,,The map {0} isn't installed! Please install it before loading this save.