Bevy: Spawing many Entities and then despawing them leads to NoSuchEntity.

[kakoeimon]

I was trying to create a minimal project for another problem an I came upon this.
The minimal example project is the example ui/text with those lines:

`struct Item {
max_time: f32,
time: f32,
}

fn add_items(mut commands: Commands) {
for _ in 0..1000 {
commands.spawn((Item {max_time: 1.0, time: 0.0}, ));
}

}

fn update_items(mut commands: Commands, time: Res, mut query: Query<(&mut Item, Entity)>) {
let mut num = 0;
for (mut item, e) in &mut query.iter() {
num += 1;
item.time += time.delta_seconds;
if item.time >= item.max_time {
commands.despawn(e);
}
}
println!("number of items : {}", num);
}`

After a while I get:

thread 'main' panicked at 'calledResult::unwrap()on anErrvalue: NoSuchEntity', C:\Users\kakoeimon\.cargo\git\checkouts\bevy-f7ffde730c324c74\89a1d36\crates\bevy_ecs\src\system\commands.rs:75:36 note: run withRUST_BACKTRACE=1environment variable to display a backtrace error: process didn't exit successfully:target\debug\no_such_entity.exe(exit code: 101)

The minimal example project

no_such_entity.zip

[CleanCut]

I confirmed I see the same thing on mac with the current master commit of https://github.com/bevyengine/bevy/commit/3efbaca10452427385822f79208ff3a78ab9edda

Here is an even more stripped down example (I just deleted more things from the example provided above).

no_such_entity.zip

[Ratysz]

Most likely related to #117.

[kakoeimon]

The example project I provided still panics.
I know it is not a real life test but...

[EllenNyan]

Are you using the git version of bevy or the crates.io version?
If you're using the crates.io version this fix wont be there until a new a release

[kakoeimon]

The git, have you tried the example project?

[EllenNyan]

Yeah it was what I used to check that the PR fixed the issue it says it does x)
Could you try running cargo clean and then rebuilding and see if that fixes it?

[memoryruins]

Be sure to cargo update the example project too. The sample project's Cargo.lock is behind in changes. Without doing so, I recreate the panic, but after updating, it goes away for me.

[kakoeimon]

Everything look OK!
cargo clean and cargo update did the trick!
Sorry for my ignorance, I will keep that in mind.
Thanks.

[EllenNyan]

Ah oops cargo update, yeah this makes sense. Glad it's working for you now ^-^

[kakoeimon]

Just to inform you, I got the bug again in my project.
Looks like it was a bad luck, but I thought it will be good to inform you.

[EllenNyan]

You'll get the same error message if you despawn the same entity twice (And from some other functions, a stacktrace would be useful if wishing to determine the actual cause :) ). Could be that

[kakoeimon]

I just found the problem and it was mine.
As you said I despawned the entity twice.
Sorry for bothering you.

[cart]

Not a problem! I'm glad you followed up, even if it ended up being on your side. It could have been an issue with bevy, and we want to fix issues with bevy :smile: