Alien Cake Addict panics in spooky way when cake is spawned on player

[rparrett]

Bevy version

b6be8a5

Operating system & version

macOS

What you did

I played a lot of alien cake addict, but here's a shortcut:

    game.bonus.i = game.player.i; //rand::thread_rng().gen_range(0..BOARD_SIZE_I);
    game.bonus.j = game.player.j; //rand::thread_rng().gen_range(0..BOARD_SIZE_J);

What actually happened

thread 'main' panicked at 'Entity does not exist', /Users/robparrett/src/bevy-fork/crates/bevy_ecs/src/world/mod.rs:214:37
stack backtrace:
   0: rust_begin_unwind
             at /rustc/cb75ad5db02783e8b0222fee363c5f63f7e2cf5b/library/std/src/panicking.rs:493:5
   1: core::panicking::panic_fmt
             at /rustc/cb75ad5db02783e8b0222fee363c5f63f7e2cf5b/library/core/src/panicking.rs:92:14
   2: core::option::expect_failed
             at /rustc/cb75ad5db02783e8b0222fee363c5f63f7e2cf5b/library/core/src/option.rs:1260:5
   3: core::option::Option<T>::expect
             at /Users/robparrett/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/src/rust/library/core/src/option.rs:349:21
   4: bevy_ecs::world::World::entity_mut
             at ./crates/bevy_ecs/src/world/mod.rs:214:9
   5: <bevy_ecs::system::commands::Insert<T> as bevy_ecs::system::commands::Command>::write
             at ./crates/bevy_ecs/src/system/commands.rs:322:9
   6: bevy_ecs::system::commands::CommandQueue::apply
             at ./crates/bevy_ecs/src/system/commands.rs:24:13
   7: <bevy_ecs::system::commands::CommandQueue as bevy_ecs::system::system_param::SystemParamState>::apply
             at ./crates/bevy_ecs/src/system/system_param.rs:447:9
   8: <(P0,P1,P2,P3) as bevy_ecs::system::system_param::SystemParamState>::apply
             at ./crates/bevy_ecs/src/system/system_param.rs:977:19
   9: <bevy_ecs::system::into_system::FunctionSystem<In,Out,Param,Marker,F> as bevy_ecs::system::system::System>::apply_buffers
             at ./crates/bevy_ecs/src/system/into_system.rs:161:9
  10: <bevy_ecs::schedule::stage::SystemStage as bevy_ecs::schedule::stage::Stage>::run
             at ./crates/bevy_ecs/src/schedule/stage.rs:689:21
  11: bevy_ecs::schedule::Schedule::run_once
             at ./crates/bevy_ecs/src/schedule/mod.rs:201:13
  12: <bevy_ecs::schedule::Schedule as bevy_ecs::schedule::stage::Stage>::run
             at ./crates/bevy_ecs/src/schedule/mod.rs:219:21
  13: bevy_app::app::App::update
             at ./crates/bevy_app/src/app.rs:58:9
  14: bevy_winit::winit_runner_with::{{closure}}
             at ./crates/bevy_winit/src/lib.rs:485:17
  15: <alloc::boxed::Box<F,A> as core::ops::function::FnMut<Args>>::call_mut
             at /Users/robparrett/.rustup/toolchains/stable-x86_64-apple-darwin/lib/rustlib/src/rust/library/alloc/src/boxed.rs:1335:9
  16: <winit::platform_impl::platform::app_state::EventLoopHandler<T> as winit::platform_impl::platform::app_state::EventHandler>::handle_nonuser_event
             at /Users/robparrett/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.24.0/src/platform_impl/macos/app_state.rs:71:9
  17: winit::platform_impl::platform::app_state::Handler::handle_nonuser_event
             at /Users/robparrett/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.24.0/src/platform_impl/macos/app_state.rs:173:21
  18: winit::platform_impl::platform::app_state::AppState::cleared
             at /Users/robparrett/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.24.0/src/platform_impl/macos/app_state.rs:331:13
  19: winit::platform_impl::platform::observer::control_flow_end_handler
             at /Users/robparrett/.cargo/registry/src/github.com-1ecc6299db9ec823/winit-0.24.0/src/platform_impl/macos/observer.rs:135:13

[alice-i-cecile]

As with the other two bugs; I think this is spooky enough to try and track down and fix before we launch.

[rparrett]

I think this is probably due to a system ordering issue between spawn_bonus and move_player.

If the cake is spawned on top of the player, move_player immediately attempts to despawn_recursive an entity that hasn't actually been added yet.