Use Null-Propagation Operator

OpenRA.Platforms.Default/OpenAlSoundEngine.cs

@@ -326,17 +326,13 @@ namespace OpenRA.Platforms.Default
 
 		public void StopSound(ISound sound)
 		{
-			if (sound == null)
-				return;
-
-			((OpenAlSound)sound).Stop();
+			((OpenAlSound)sound)?.Stop();
 		}
 
 		public void StopAllSounds()
 		{
 			foreach (var slot in sourcePool.Values)
-				if (slot.Sound != null)
-					slot.Sound.Stop();
+				slot.Sound?.Stop();
 		}
 
 		public void SetListenerPosition(WPos position)

OpenRA.Platforms.Default/Sdl2PlatformWindow.cs

@@ -415,8 +415,7 @@ namespace OpenRA.Platforms.Default
 
 			disposed = true;
 
-			if (context != null)
-				context.Dispose();
+			context?.Dispose();
 
 			if (Window != IntPtr.Zero)
 				SDL.SDL_DestroyWindow(Window);

OpenRA.Platforms.Default/ThreadedGraphicsContext.cs

@@ -260,8 +260,7 @@ namespace OpenRA.Platforms.Default
 				var localResult = result;
 				result = null;
 
-				if (localEdi != null)
-					localEdi.Throw();
+				localEdi?.Throw();
 				return localResult;
 			}
 		}
@@ -278,8 +277,7 @@ namespace OpenRA.Platforms.Default
 		void QueueMessage(Message message)
 		{
 			var exception = messageException;
-			if (exception != null)
-				exception.Throw();
+			exception?.Throw();
 
 			lock (messages)
 			{