Fix PistonCalculator for normal Pistons

BauSystem_Main/src/de/steamwar/bausystem/features/util/PistonCalculator.java

@@ -50,13 +50,18 @@ public class PistonCalculator implements Listener {
     @EventHandler
     public void onPlayerInteract(PlayerInteractEvent event) {
         if (event.getAction() != Action.RIGHT_CLICK_BLOCK) return;
-        if (event.getPlayer().getInventory().getItemInMainHand().getType() != Material.SLIME_BALL) return;
+        if (!event.hasItem() || event.getItem().getType() != Material.SLIME_BALL) return;
         if (event.getClickedBlock() == null) return;
         Block clickedBlock = event.getClickedBlock();
         Material blockType = clickedBlock.getType();
         if (!(blockType == Material.PISTON || blockType == Material.STICKY_PISTON)) return;
         Piston piston = (Piston) clickedBlock.getBlockData();
 
+        if (blockType == Material.PISTON && piston.isExtended()) {
+            BauSystem.MESSAGE.sendPrefixless("PISTON_INFO", event.getPlayer(), ChatMessageType.ACTION_BAR, "§a", 0);
+            return;
+        }
+
         boolean pulling = blockType == Material.STICKY_PISTON && (clickedBlock.getRelative(piston.getFacing()).getType() == Material.AIR || piston.isExtended());
 
         CalculationResult result = calc(clickedBlock, piston.getFacing(), (pulling ? piston.getFacing().getOppositeFace() : piston.getFacing()));