Panic "no empty slots available in array" when despawning entities

[DGriffin91]

I'm getting an error when trying to despawn cubes in a system:
thread 'main' panicked at 'no empty slots available in array' [...]render_graph\nodes\render_resources_node.rs:50:17

It despawns the first one fine, then crashes. In my example I am spawning a cube every second and then despawning them when they move to a specific point. Do I need to free any render resources?

I put together a fairly minimal example here as a gist:
https://gist.github.com/DGriffin91/b592d4ce3ca8ea99204c9ba9a057b74c

Not sure if I am doing something wrong, or if this is a bug.

[DGriffin91]

Just noticed there is already an issue about this: #135
Closing this duplicate one...