Fix PVS exception (#5196)

Robust.Server/GameObjects/EntitySystems/UserInterfaceSystem.cs

@@ -1,6 +1,7 @@
 using System.Collections.Generic;
 using Robust.Server.GameStates;
 using Robust.Shared.GameObjects;
+using Robust.Shared.Utility;
 
 namespace Robust.Server.GameObjects;
 
@@ -23,6 +24,8 @@ public sealed class UserInterfaceSystem : SharedUserInterfaceSystem
 
         foreach (var ui in buis)
         {
+            DebugTools.Assert(ent.Comp.OpenInterfaces[ui].Count > 0);
+            DebugTools.Assert(HasComp<UserInterfaceComponent>(ui));
             args.Entities.Add(ui);
         }
     }

Robust.Server/GameStates/PvsSystem.Overrides.cs

@@ -100,7 +100,13 @@ internal sealed partial class PvsSystem
     /// </summary>
     private bool RecursivelyAddOverride(PvsSession session, EntityUid uid, GameTick fromTick, bool addChildren)
     {
-        var xform = _xformQuery.GetComponent(uid);
+        if (!_xformQuery.TryGetComponent(uid, out var xform))
+        {
+            // Can happen if systems add deleted entities to PVS move event.
+            Log.Error($"Attempted to add non-existent entity {uid} to PVS override for session {session.Session}");
+            return false;
+        }
+
         var parent = xform.ParentUid;
 
         // First we process all parents. This is because while this entity may already have been added