Add optional registry utils to TagUtil (#3819)

Author: FlorianMichael

common/src/main/java/com/viaversion/viaversion/util/TagUtil.java

@@ -26,19 +26,33 @@
 public final class TagUtil {
 
     public static ListTag<CompoundTag> getRegistryEntries(final CompoundTag tag, final String key) {
+        return getRegistryEntries(tag, key, null);
+    }
+
+    public static ListTag<CompoundTag> getRegistryEntries(final CompoundTag tag, final String key, final @Nullable ListTag<CompoundTag> defaultValue) {
         CompoundTag registry = tag.getCompoundTag(Key.namespaced(key));
         if (registry == null) {
             registry = tag.getCompoundTag(Key.stripMinecraftNamespace(key));
+            if (registry == null) {
+                return defaultValue;
+            }
         }
         return registry.getListTag("value", CompoundTag.class);
     }
 
     public static ListTag<CompoundTag> removeRegistryEntries(final CompoundTag tag, final String key) {
+        return removeRegistryEntries(tag, key, null);
+    }
+
+    public static ListTag<CompoundTag> removeRegistryEntries(final CompoundTag tag, final String key, final @Nullable ListTag<CompoundTag> defaultValue) {
         String currentKey = Key.namespaced(key);
         CompoundTag registry = tag.getCompoundTag(currentKey);
         if (registry == null) {
             currentKey = Key.stripMinecraftNamespace(key);
             registry = tag.getCompoundTag(currentKey);
+            if (registry == null) {
+                return defaultValue;
+            }
         }
         tag.remove(currentKey);
         return registry.getListTag("value", CompoundTag.class);