fix NPE when iterating over default drops (#10017)

patches/server/Restore-vanilla-entity-drops-behavior.patch

@@ -188,12 +188,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          lootCheck.run(); // Paper - advancement triggers before destroying items
  
 -        for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
--            if (stack == null || stack.getType() == Material.AIR || stack.getAmount() == 0) continue;
 +        // Paper start
 +        for (Entity.DefaultDrop drop : drops) {
++            if (drop == null) continue;;
 +            final org.bukkit.inventory.ItemStack stack = drop.stack();
-+            if (drop == null || stack == null || stack.getType() == Material.AIR || stack.getAmount() == 0) continue;
 +            // Paper end
+             if (stack == null || stack.getType() == Material.AIR || stack.getAmount() == 0) continue;
  
 -            world.dropItem(entity.getLocation(), stack); // Paper - note: dropItem already clones due to this being bukkit -> NMS
 +            drop.runConsumer(world, entity.getLocation()); // Paper
@@ -216,12 +216,12 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          victim.newExp = event.getNewExp();
  
 -        for (org.bukkit.inventory.ItemStack stack : event.getDrops()) {
--            if (stack == null || stack.getType() == Material.AIR) continue;
 +        // Paper start
 +        for (Entity.DefaultDrop drop : drops) {
++            if (drop == null) continue;
 +            final org.bukkit.inventory.ItemStack stack = drop.stack();
-+            if (drop == null || stack == null || stack.getType() == Material.AIR) continue;
 +            // Paper end
+             if (stack == null || stack.getType() == Material.AIR) continue;
  
 -            world.dropItem(entity.getLocation(), stack);
 +            drop.runConsumer(world, entity.getLocation()); // Paper