Index: ps/trunk/binaries/data/mods/public/gui/gamesetup/Controls/GameSettingsControl.js
===================================================================
--- ps/trunk/binaries/data/mods/public/gui/gamesetup/Controls/GameSettingsControl.js
+++ ps/trunk/binaries/data/mods/public/gui/gamesetup/Controls/GameSettingsControl.js
@@ -8,7 +8,7 @@
 	{
 		this.startGameControl = startGameControl;
 		this.mapCache = mapCache;
-		this.gameSettingsFile = new GameSettingsFile(setupWindow);
+		this.gameSettingsFile = new GameSettingsFile(this);
 
 		this.previousMap = undefined;
 		this.depth = 0;
@@ -28,6 +28,8 @@
 
 		startGameControl.registerLaunchGameHandler(this.onLaunchGame.bind(this));
 
+		setupWindow.registerClosePageHandler(this.onClose.bind(this));
+
 		if (g_IsNetworked)
 			netMessages.registerNetMessageHandler("gamesetup", this.onGamesetupMessage.bind(this));
 	}
@@ -134,6 +136,12 @@
 		}
 	}
 
+	onClose()
+	{
+		if (!this.autostart)
+			this.gameSettingsFile.saveFile();
+	}
+
 	onGetHotloadData(object)
 	{
 		object.gameAttributes = g_GameAttributes;
@@ -183,9 +191,18 @@
 		if (g_GameAttributes.map && this.previousMap != g_GameAttributes.map && g_GameAttributes.mapType)
 		{
 			this.previousMap = g_GameAttributes.map;
-			let mapData = this.mapCache.getMapData(g_GameAttributes.mapType, g_GameAttributes.map);
-			for (let handler of this.mapChangeHandlers)
-				handler(mapData);
+			// Use a try..catch to avoid completely failing in case of an error
+			// as this prevents even going back to the main menu.
+			try
+			{
+				let mapData = this.mapCache.getMapData(g_GameAttributes.mapType, g_GameAttributes.map);
+				for (let handler of this.mapChangeHandlers)
+					handler(mapData);
+			} catch(err) {
+				// Report the error regardless so that the underlying bug gets fixed.
+				error(err);
+				error(err.stack);
+			}
 		}
 
 		for (let handler of this.gameAttributesChangeHandlers)
Index: ps/trunk/binaries/data/mods/public/gui/gamesetup/Controls/GameSettingsFile.js
===================================================================
--- ps/trunk/binaries/data/mods/public/gui/gamesetup/Controls/GameSettingsFile.js
+++ ps/trunk/binaries/data/mods/public/gui/gamesetup/Controls/GameSettingsFile.js
@@ -3,7 +3,7 @@
  */
 class GameSettingsFile
 {
-	constructor(setupWindow)
+	constructor(GameSettingsControl)
 	{
 		this.filename = g_IsNetworked ?
 			this.GameAttributesFileMultiplayer :
@@ -11,8 +11,6 @@
 
 		this.engineInfo = Engine.GetEngineInfo();
 		this.enabled = Engine.ConfigDB_GetValue("user", this.ConfigName) == "true";
-
-		setupWindow.registerClosePageHandler(this.saveFile.bind(this));
 	}
 
 	loadFile()
Index: ps/trunk/binaries/data/mods/public/gui/gamesetup/Pages/GameSetupPage/GameSettings/Single/Dropdowns/PopulationCap.js
===================================================================
--- ps/trunk/binaries/data/mods/public/gui/gamesetup/Pages/GameSetupPage/GameSettings/Single/Dropdowns/PopulationCap.js
+++ ps/trunk/binaries/data/mods/public/gui/gamesetup/Pages/GameSetupPage/GameSettings/Single/Dropdowns/PopulationCap.js
@@ -30,7 +30,7 @@
 
 		this.perPlayer =
 			isScenario &&
-			mapData.settings.PlayerData &&
+			mapData && mapData.settings && mapData.settings.PlayerData &&
 			mapData.settings.PlayerData.some(pData => pData && pData.PopulationLimit !== undefined);
 
 		this.setEnabled(!isScenario && !this.perPlayer);
Index: ps/trunk/binaries/data/mods/public/gui/gamesetup/Pages/GameSetupPage/GameSettings/Single/Dropdowns/StartingResources.js
===================================================================
--- ps/trunk/binaries/data/mods/public/gui/gamesetup/Pages/GameSetupPage/GameSettings/Single/Dropdowns/StartingResources.js
+++ ps/trunk/binaries/data/mods/public/gui/gamesetup/Pages/GameSetupPage/GameSettings/Single/Dropdowns/StartingResources.js
@@ -40,7 +40,7 @@
 
 		this.perPlayer =
 			isScenario &&
-			mapData.settings.PlayerData &&
+			mapData && mapData.settings && mapData.settings.PlayerData &&
 			mapData.settings.PlayerData.some(pData => pData && pData.Resources !== undefined);
 
 		this.setEnabled(!isScenario && !this.perPlayer);