Bevymark sometimes panics with "Called `Result::unwrap()` on an `Err` value"

## Bevy version

Bevy Git (299bd37)

## What you did

1. Run bevymark.
3. Close the app window.

## What went wrong

- What were you expecting?

The app gracefully exits.

- What actually happened?

The app crashes due to the `window.single()` call after the window has been closed.
https://github.com/bevyengine/bevy/blob/299bd3775274a250e9db48251111796e491e92ff/examples/stress_tests/bevymark.rs#L73

## Additional information

Logs:

```
C:/Users/User/.cargo/bin/cargo.exe run --color=always --package bevy --example bevymark --release
Finished release [optimized] target(s) in 1.02s
Running `target\release\examples\bevymark.exe`
2023-01-28T20:27:12.022073Z INFO bevy_winit::system: Creating new window "BevyMark" (0v0)
2023-01-28T20:27:12.339709Z INFO bevy_render::renderer: AdapterInfo { name: "Intel(R) UHD Graphics 620", vendor: 32902, device: 22807, device_type: IntegratedGpu, driver: "Intel Corporation", driver_info: "Intel driver", backend: Vulkan }
2023-01-28T20:27:12.576022Z WARN bevymark: This is a stress test used to push Bevy to its limit and debug performance issues. It is not representative of an actual game. It must be run in release mode using --release or it will be very slow.
2023-01-28T20:27:12.993780Z INFO bevy_diagnostic::system_information_diagnostics_plugin::internal: SystemInfo { os: "Windows 11 Pro for Workstations", kernel: "22621", cpu: "Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz", core_count: "4", memory: "7.9 GiB" }
2023-01-28T20:27:13.605354Z INFO bevy diagnostic: frame_time : 12.304128ms (avg 9.301445ms)
2023-01-28T20:27:13.605426Z INFO bevy diagnostic: fps : 103.083789 (avg 127.180158)
2023-01-28T20:27:13.605452Z INFO bevy diagnostic: frame_count : 34.000000
2023-01-28T20:27:14.610938Z INFO bevy diagnostic: frame_time : 26.047071ms (avg 35.430010ms)
2023-01-28T20:27:14.611030Z INFO bevy diagnostic: fps : 73.854242 (avg 61.802481)
2023-01-28T20:27:14.611108Z INFO bevy diagnostic: frame_count : 72.000000
2023-01-28T20:27:16.000367Z INFO bevy diagnostic: frame_time : 99.458159ms (avg 59.436820ms)
2023-01-28T20:27:16.000422Z INFO bevy diagnostic: fps : 18.614649 (avg 33.649745)
2023-01-28T20:27:16.000439Z INFO bevy diagnostic: frame_count : 99.000000
2023-01-28T20:27:16.614072Z INFO bevy diagnostic: frame_time : 52.782843ms (avg 64.720315ms)
2023-01-28T20:27:16.614144Z INFO bevy diagnostic: fps : 21.400037 (avg 31.669169)
2023-01-28T20:27:16.614175Z INFO bevy diagnostic: frame_count : 113.000000
2023-01-28T20:27:17.674446Z INFO bevy diagnostic: frame_time : 85.278767ms (avg 68.694300ms)
2023-01-28T20:27:17.674517Z INFO bevy diagnostic: fps : 11.852638 (avg 16.147101)
2023-01-28T20:27:17.674544Z INFO bevy diagnostic: frame_count : 127.000000
thread 'Compute Task Pool (0)' panicked at 'called `Result::unwrap()` on an `Err` value: NoEntities("bevy_ecs::query::state::QueryState<&bevy_window::window::Window>")', examples/stress_tests/bevymark.rs:73:26
stack backtrace:
0: std::panicking::begin_panic_handler
at /rustc/ef982929c0b653436a6ea6892a2a839fba7c8b57/library\std\src\panicking.rs:575
1: core::panicking::panic_fmt
at /rustc/ef982929c0b653436a6ea6892a2a839fba7c8b57/library\core\src\panicking.rs:64
2: core::result::unwrap_failed
at /rustc/ef982929c0b653436a6ea6892a2a839fba7c8b57/library\core\src\result.rs:1790
3: bevy_ecs::system::query::Query::single
4: core::ops::function::impls:: for &mut F>::call_mut
5: as bevy_ecs::system::system::System>::run_unsafe
6: async_task::raw::RawTask::run
7: as core::future::future::Future>::poll
8: async_executor::Executor::run::{{closure}}
9: std::thread::local::LocalKey::with
10: std::thread::local::LocalKey::with
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', C:\Users\User\source\repos\bevy\crates\bevy_tasks\src\task_pool.rs:354:49
stack backtrace:
0: std::panicking::begin_panic_handler
at /rustc/ef982929c0b653436a6ea6892a2a839fba7c8b57/library\std\src\panicking.rs:575
1: core::panicking::panic_fmt
at /rustc/ef982929c0b653436a6ea6892a2a839fba7c8b57/library\core\src\panicking.rs:64
2: core::panicking::panic
at /rustc/ef982929c0b653436a6ea6892a2a839fba7c8b57/library\core\src\panicking.rs:114
3: bevy_tasks::thread_executor::ThreadExecutorTicker::tick::{{closure}}
4: as core::future::future::Future>::poll
5: bevy_ecs::system::system_param::assert_component_access_compatibility
6: std::thread::local::LocalKey::with
7: bevy_tasks::task_pool::TaskPool::scope_with_executor_inner
8: ::run_systems
9: ::run
10: bevy_ecs::schedule::Schedule::run_once
11: bevy_app::app::App::update
12: winit::platform_impl::platform::event_loop::EventLoop::run_return::{{closure}}
13: as core::ops::function::FnOnce<()>>::call_once
14: winit::platform_impl::platform::event_loop::runner::EventLoopRunner::register_window
15: winit::platform_impl::platform::event_loop::runner::EventLoopRunner::move_state_to
16: as core::ops::function::FnOnce<()>>::call_once
17: winit::platform_impl::platform::event_loop::runner::EventLoopRunner::catch_unwind
18: winit::platform_impl::platform::event_loop::EventLoopThreadExecutor::execute_in_thread
19: DispatchMessageW
20: DispatchMessageW
21: GetClassLongW
22: KiUserCallbackDispatcher
23: NtUserDispatchMessage
24: DispatchMessageW
25: winit::platform_impl::platform::event_loop::EventLoop::run_return
26: winit::platform_impl::platform::event_loop::EventLoop::run
27: >::into
28: ::build
29: bevy_winit::winit_runner
30: core::ops::function::Fn::call
31: bevy_app::app::App::run
32: >::into_descriptor
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.
error: process didn't exit successfully: `target\release\examples\bevymark.exe` (exit code: 101)
```