Synchronized tile modification with updating

core/src/io/anuke/mindustry/entities/TileEntity.java

@@ -106,17 +106,19 @@ public class TileEntity extends Entity{
 	
 	@Override
 	public void update(){
-		if(health != 0 && health < tile.block().health && !(tile.block() instanceof Wall) &&
-				Mathf.chance(0.009f*Timers.delta()*(1f-health/tile.block().health))){
+		synchronized (tile) {
+			if (health != 0 && health < tile.block().health && !(tile.block() instanceof Wall) &&
+					Mathf.chance(0.009f * Timers.delta() * (1f - health / tile.block().health))) {
 
-			Effects.effect(Fx.smoke, x+Mathf.range(4), y+Mathf.range(4));
-		}
+				Effects.effect(Fx.smoke, x + Mathf.range(4), y + Mathf.range(4));
+			}
 
-		if(health <= 0){
-			onDeath();
+			if (health <= 0) {
+				onDeath();
+			}
+
+			tile.block().update(tile);
 		}
-		
-		tile.block().update(tile);
 	}
 	
 	public int totalItems(){

core/src/io/anuke/mindustry/world/Tile.java

@@ -260,18 +260,20 @@ public class Tile{
 	}
 	
 	public void changed(){
-		if(entity != null){
-			entity.remove();
-			entity = null;
-		}
-		
-		Block block = block();
-		
-		if(block.destructible || block.update){
-			entity = block.getEntity().init(this, block.update);
-		}
+		synchronized (this) {
+			if (entity != null) {
+				entity.remove();
+				entity = null;
+			}
 
-		updateOcclusion();
+			Block block = block();
+
+			if (block.destructible || block.update) {
+				entity = block.getEntity().init(this, block.update);
+			}
+
+			updateOcclusion();
+		}
 	}
 	
 	@Override

core/src/io/anuke/mindustry/world/blocks/types/distribution/Conveyor.java

@@ -143,7 +143,6 @@ public class Conveyor extends Block{
 
 	@Override
 	public boolean acceptItem(Item item, Tile tile, Tile source){
-		if(tile.entity == null) return false;
 		int direction = source == null ? 0 : Math.abs(source.relativeTo(tile.x, tile.y) - tile.getRotation());
 		float minitem = tile.<ConveyorEntity>entity().minitem;
 		return (((direction == 0) && minitem > 0.05f) ||