updates

src/main/java/com/loganmagnan/unlimiteditems/listeners/EntityPickupItemListener.java

@@ -35,6 +35,10 @@ public class EntityPickupItemListener implements Listener {
 
         ItemStack itemStackOne = event.getItem().getItemStack();
 
+        if (!this.isMaterialStackable(itemStackOne)) {
+            return;
+        }
+
         event.setCancelled(true);
         event.getItem().remove();
 
@@ -86,4 +90,12 @@ public class EntityPickupItemListener implements Listener {
 
         player.updateInventory();
     }
+
+    public boolean isMaterialStackable(ItemStack itemStack) {
+        if (itemStack == null || itemStack.getType() == Material.AIR) {
+            return false;
+        }
+
+        return itemStack.getMaxStackSize() > 1;
+    }
 }