Fix sending CUI packets to unwilling clients.

Some servers track channel registration: NF throws an error every time this happens; Bukkit silently drops it; Fabric silently sends it (presumably the client ignores it).

Author: wizjany

worldedit-core/src/main/java/com/sk89q/worldedit/LocalSession.java

@@ -957,8 +957,10 @@ public void dispatchCUISetup(Actor actor) {
     public void dispatchCUISelection(Actor actor) {
         checkNotNull(actor);
 
-        if (!hasCUISupport && useServerCUI) {
-            updateServerCUI(actor);
+        if (!hasCUISupport) {
+            if (useServerCUI) {
+                updateServerCUI(actor);
+            }
             return;
         }