fix(schedules): protect against null schedules

src/MfGames.Nitride.Temporal.Schedules/ApplySchedules.cs

@@ -49,6 +49,15 @@ public partial class ApplySchedules : OperationBase
         return input.Select(this.Apply);
     }
 
+    /// <summary>
+    /// Adds a single schedule into the apply schedules and returns the ApplySchedule
+    /// class.
+    /// </summary>
+    public ApplySchedules WithGetSchedules(Func<Entity, ISchedule> schedule)
+    {
+        return this.WithGetSchedules(entity => new[] { schedule(entity) });
+    }
+
     public ApplySchedules WithGetSchedules<TType>(
         Func<Entity, IEnumerable<TType>?> value)
         where TType : ISchedule
@@ -74,7 +83,7 @@ public partial class ApplySchedules : OperationBase
         // Otherwise, apply the schedules to this entity.
         foreach (ISchedule schedule in schedules)
         {
-            if (!schedule.CanApply(entity))
+            if (schedule == null! || !schedule.CanApply(entity))
             {
                 continue;
             }