fix #179

Author: brachy84

src/main/java/com/cleanroommc/modularui/value/sync/PanelSyncManager.java

@@ -99,6 +99,7 @@ public void onOpen() {
     @ApiStatus.Internal
     public void onClose() {
         this.closeListener.forEach(listener -> listener.accept(getPlayer()));
+        this.syncHandlers.values().forEach(SyncHandler::dispose);
         // Previously panel sync handlers were removed from the main psm, however this problematic if the screen will be reopened at some
         // point. We can just not remove the sync handlers since mui has proper checks for re-registering panels.
     }