Fix Android startup crash: guard assembly loading, null-check host window, prevent division by zero

Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/2d6db8b8-e94e-4a7e-9e29-c6d7a9c9cbc9

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot

osu.Android/OsuGameActivity.cs

@@ -117,10 +117,17 @@ protected override void OnCreate(Bundle? savedInstanceState)
             // Manually load them so that they can be loaded by RulesetStore.loadFromAppDomain.
             // REMEMBER to fully uninstall previous version every time when investigating this!
             // Don't forget osu.Game.Tests.Android too.
-            Assembly.Load("osu.Game.Rulesets.Osu");
-            Assembly.Load("osu.Game.Rulesets.Taiko");
-            Assembly.Load("osu.Game.Rulesets.Catch");
-            Assembly.Load("osu.Game.Rulesets.Mania");
+            foreach (string asm in new[] { "osu.Game.Rulesets.Osu", "osu.Game.Rulesets.Taiko", "osu.Game.Rulesets.Catch", "osu.Game.Rulesets.Mania" })
+            {
+                try
+                {
+                    Assembly.Load(asm);
+                }
+                catch (Exception e)
+                {
+                    Debug.WriteLine($"[osu!] Failed to load ruleset assembly {asm}: {e.Message}");
+                }
+            }
         }
 
         protected override void OnResume()

osu.Android/OsuGameAndroid.cs

@@ -28,7 +28,9 @@ public partial class OsuGameAndroid : OsuGame
 
         private readonly PackageInfo? packageInfo;
 
-        public override Vector2 ScalingContainerTargetDrawSize => new Vector2(1024, 1024 * DrawHeight / DrawWidth);
+        public override Vector2 ScalingContainerTargetDrawSize => DrawWidth > 0
+            ? new Vector2(1024, 1024 * DrawHeight / DrawWidth)
+            : new Vector2(1024, 768);
 
         private readonly Bindable<bool> performanceMode = new Bindable<bool>();
         private readonly Bindable<bool> lowLatencyAudio = new Bindable<bool>();
@@ -305,7 +307,9 @@ private void updateOrientation()
         public override void SetHost(GameHost host)
         {
             base.SetHost(host);
-            host.Window.CursorState |= CursorState.Hidden;
+
+            if (host.Window != null)
+                host.Window.CursorState |= CursorState.Hidden;
         }
 
         protected override UpdateManager CreateUpdateManager() => new MobileUpdateNotifier();