Fix barber scissors cancel errors (#40329)

Fix

Content.Server/MagicMirror/MagicMirrorSystem.cs

@@ -107,6 +107,8 @@ public sealed class MagicMirrorSystem : SharedMagicMirrorSystem
 
     private void OnSelectSlotDoAfter(EntityUid uid, MagicMirrorComponent component, MagicMirrorSelectDoAfterEvent args)
     {
+        component.DoAfter = null;
+
         if (args.Handled || args.Target == null || args.Cancelled)
             return;
 
@@ -185,6 +187,8 @@ public sealed class MagicMirrorSystem : SharedMagicMirrorSystem
     }
     private void OnChangeColorDoAfter(EntityUid uid, MagicMirrorComponent component, MagicMirrorChangeColorDoAfterEvent args)
     {
+        component.DoAfter = null;
+
         if (args.Handled || args.Target == null || args.Cancelled)
             return;
 
@@ -265,6 +269,8 @@ public sealed class MagicMirrorSystem : SharedMagicMirrorSystem
 
     private void OnRemoveSlotDoAfter(EntityUid uid, MagicMirrorComponent component, MagicMirrorRemoveSlotDoAfterEvent args)
     {
+        component.DoAfter = null;
+
         if (args.Handled || args.Target == null || args.Cancelled)
             return;
 
@@ -342,6 +348,8 @@ public sealed class MagicMirrorSystem : SharedMagicMirrorSystem
     }
     private void OnAddSlotDoAfter(EntityUid uid, MagicMirrorComponent component, MagicMirrorAddSlotDoAfterEvent args)
     {
+        component.DoAfter = null;
+
         if (args.Handled || args.Target == null || args.Cancelled || !TryComp(component.Target, out HumanoidAppearanceComponent? humanoid))
             return;