fix manabar cue issue

scenes/player_controller/PlayerUi.cs

@@ -90,16 +90,9 @@ public partial class PlayerUi : Control, ICueHandler
 
     public void OnExecute(IForgeEntity? target, CueParameters? parameters)
     {
-        // One-shot effect (like impact)
-        // Called when an instant effect with this cue is applied
-        // Also called when a periodic effect with this cue executes its period
-        if (target == null || !parameters.HasValue) return;
+        if (target == null || !parameters.HasValue || !IsInstanceValid(_manabar)) return;
 
-        // Extract parameters
         float magnitude = parameters.Value.Magnitude;
-        // Play effects scaled by magnitude
-        // PlayFireImpactSound(normalizedMagnitude);
-        // SpawnFireImpactParticles(target, magnitude);
         _manabar.CurrentHealth += magnitude;
     }