Crash fix

core/src/io/anuke/mindustry/entities/traits/BuilderTrait.java

@@ -213,8 +213,8 @@ public interface BuilderTrait extends Entity, TeamTrait{
 
         TileEntity core = unit.getClosestCore();
 
-        //if there is no core to build with, stop building!
-        if(core == null){
+        //if there is no core to build with or no build entity, stop building!
+        if(core == null || !(tile.entity instanceof BuildEntity)){
             return;
         }
 

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

@@ -280,7 +280,9 @@ public class TileEntity extends BaseEntity implements TargetTrait, HealthTrait{
 
         if(health <= 0){
             onDeath();
+            return; //no need to update anymore
         }
+
         Block previous = block;
         block.update(tile);
         if(block == previous && cons != null){

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

@@ -199,7 +199,6 @@ public class Conveyor extends Block{
 
     @Override
     public void update(Tile tile){
-
         ConveyorEntity entity = tile.entity();
         entity.minitem = 1f;
         Tile next = tile.getNearby(tile.getRotation());