Fix closing already closed channel on exit

game/game.go

@@ -410,7 +410,13 @@ func (g *Game) Cleanup() {
 			rl.UnloadMusicStream(g.AssetManager.Music)
 		}
 
-		close(g.quitChan)
+		// Only close the channel if it hasn't been closed yet
+		select {
+		case <-g.quitChan:
+			// Channel already closed, do nothing
+		default:
+			close(g.quitChan)
+		}
 	})
 }
 
@@ -491,7 +497,8 @@ func (g *Game) DrawMenu() {
 }
 
 func (g *Game) Shutdown() {
-	close(g.quitChan)
+	// Use the cleanup method which has channel-closing safety
+	g.Cleanup()
 }
 
 func (g *Game) HandleServerMessages(messages []*pb.ChatMessage) {