Check if Items of campfire block entity is null (#3986)

* Check if items of campfire block entity is null
* Use instanceof for Items

core/src/main/java/org/geysermc/geyser/translator/level/block/entity/CampfireBlockEntityTranslator.java

@@ -39,11 +39,12 @@ import org.geysermc.geyser.registry.type.ItemMapping;
 public class CampfireBlockEntityTranslator extends BlockEntityTranslator {
     @Override
     public void translateTag(NbtMapBuilder builder, CompoundTag tag, int blockState) {
-        ListTag items = tag.get("Items");
-        int i = 1;
-        for (Tag itemTag : items.getValue()) {
-            builder.put("Item" + i, getItem((CompoundTag) itemTag));
-            i++;
+        if (tag.get("Items") instanceof ListTag items) {
+            int i = 1;
+            for (Tag itemTag : items.getValue()) {
+                builder.put("Item" + i, getItem((CompoundTag) itemTag));
+                i++;
+            }
         }
     }