less serialize code

include/td/game/World.h

@@ -61,7 +61,7 @@ class World {
 
 	TilePtr GetTilePtr(TileIndex index) const {
 		if (index == 0)
-			return nullptr;
+			return TilePtr(nullptr);
 		return m_TilePalette.at(index - 1);
 	}
 

include/td/game/WorldTypes.h

@@ -67,7 +67,7 @@ using TileFactory = sp::MessageFactory<Tile, AllTiles>;
 
 class TileHandler : public sp::GenericHandler<AllTiles> {};
 
-using TilePtr = std::shared_ptr<sp::SerializableMessage<TileFactory>>;
+using TilePtr = sp::SerializableMessage<TileFactory>;
 
 // typedef std::shared_ptr<Tile> TilePtr;
 typedef std::vector<std::uint16_t> ChunkPalette;