fix: return compound tag instead of end tag for empty Ops value (#3406)

Author: PierreSchwang

worldedit-bukkit/adapters/adapter-1_21_11/src/main/java/com/sk89q/worldedit/bukkit/adapter/impl/fawe/v1_21_11/LinOps.java

@@ -54,13 +54,14 @@
 public class LinOps implements DynamicOps<LinTag<?>> {
 
     static final DynamicOps<LinTag<?>> INSTANCE = new LinOps();
+    private static final LinTag<?> EMPTY_TAG = LinCompoundTag.of(Map.of());
 
     private LinOps() {
     }
 
     @Override
     public LinTag<?> empty() {
-        return LinEndTag.instance();
+        return EMPTY_TAG;
     }
 
     @Override
@@ -70,7 +71,7 @@ public LinTag<?> emptyList() {
 
     @Override
     public LinTag<?> emptyMap() {
-        return LinCompoundTag.builder().build();
+        return EMPTY_TAG;
     }
 
     @Override