Fix SimpleExecutor crash

crates/bevy_ecs/src/schedule/executor/simple.rs

@@ -4,7 +4,9 @@ use fixedbitset::FixedBitSet;
 use std::panic::AssertUnwindSafe;
 
 use crate::{
-    schedule::{BoxedCondition, ExecutorKind, SystemExecutor, SystemSchedule},
+    schedule::{
+        executor::is_apply_deferred, BoxedCondition, ExecutorKind, SystemExecutor, SystemSchedule,
+    },
     world::World,
 };
 
@@ -86,6 +88,10 @@ impl SystemExecutor for SimpleExecutor {
             }
 
             let system = &mut schedule.systems[system_index];
+            if is_apply_deferred(system) {
+                continue;
+            }
+
             let res = std::panic::catch_unwind(AssertUnwindSafe(|| {
                 system.run((), world);
             }));
@@ -125,3 +131,16 @@ fn evaluate_and_fold_conditions(conditions: &mut [BoxedCondition], world: &mut W
         .map(|condition| condition.run((), world))
         .fold(true, |acc, res| acc && res)
 }
+
+#[cfg(test)]
+#[test]
+fn skip_automatic_sync_points() {
+    // Schedules automatically insert appy_deferred systems, but these should
+    // not be executed as they only serve as markers and are not initialized
+    use crate::prelude::*;
+    let mut sched = Schedule::default();
+    sched.set_executor_kind(ExecutorKind::Simple);
+    sched.add_systems((|_: Commands| (), || ()).chain());
+    let mut world = World::new();
+    sched.run(&mut world);
+}