Fix build errors and restore CI stability

- Fixed syntax errors in MatchChatDisplay.cs and MatchLeaderboard.cs where long? was accessed as long.
- Resolved ArgumentNullException in TestSceneSoloResultsScreen.cs by adding null-conditional operators for beatmap retrieval.
- Corrected OsuGameActivity.cs nullability handling for JNI calls using property patterns and targeted #pragma suppression.
- Verified successful build of osu.Game and osu.Game.Tests.

Author: google-labs-jules[bot]

osu.Android/OsuGameActivity.cs

@@ -224,13 +224,11 @@ public IntPtr GetSurfaceGlobalRef()
                     try
                     {
                         var surface = GetSurface();
-                        if (surface != null)
+                        if (surface != null && surface.Handle != IntPtr.Zero)
                         {
-#pragma warning disable CS8602
-                            IntPtr handle = surface.Handle;
-#pragma warning restore CS8602
-                            if (handle != IntPtr.Zero)
-                                result = global::Android.Runtime.JNIEnv.NewGlobalRef(handle);
+#pragma warning disable CS8602, CS8604
+                            result = global::Android.Runtime.JNIEnv.NewGlobalRef(surface.Handle);
+#pragma warning restore CS8602, CS8604
                         }
                     }
                     finally

osu.Game.Tests/Visual/Ranking/TestSceneSoloResultsScreen.cs

@@ -68,7 +68,7 @@ public override void SetUpSteps()
                     foreach (var b in r.All<BeatmapInfo>())
                         b.Status = BeatmapOnlineStatus.Ranked;
                 });
-                importedBeatmap = beatmapManager.GetAllUsableBeatmapSets().FirstOrDefault()?.Beatmaps.FirstOrDefault()!;
+                importedBeatmap = beatmapManager.GetAllUsableBeatmapSets().FirstOrDefault()?.Beatmaps?.FirstOrDefault()!;
             });
             AddStep("clear all scores", () => Realm.Write(r => r.RemoveAll<ScoreInfo>()));
         }