Fix crash when player entity is null

src/Client/EntityCarryRenderer.cs

@@ -63,6 +63,11 @@ private CachedCarryableBlock GetCachedBlock(CarriedBlock carried)
 		public void OnRenderFrame(float deltaTime, EnumRenderStage stage)
 		{
 			foreach (var player in API.World.AllPlayers) {
+				// Player entity may be null in some circumstances.
+				// Maybe the other player is too far away, so there's
+				// no entity spawned for them on the client's side?
+				if (player.Entity == null) continue;
+
 				// Don't render anything on the client player if they're in first person.
 				if ((API.World.Player.CameraMode == EnumCameraMode.FirstPerson)
 					&& (player == API.World.Player)) continue;

src/Handler/CarryHandler.cs

@@ -48,6 +48,8 @@ public void OnPress()
 				if (!world.BlockAccessor.GetBlock(_selectedBlock).IsCarryable()) return;
 				_action = CurrentAction.PickUp;
 			} else {
+				// Place down a block. Make sure it's
+				// put on a solid top face of a block.
 				if (!CanPlace(world, selection, carried)) return;
 				_action = CurrentAction.PlaceDown;
 			}