Consider using std::sync::mpsc instead of crossbeam-channel

[namse]

How about using std::sync::mpsc instead of crossbeam-channel?

As far as I know, the channel code from crossbeam-channel has been merged into the standard library's std::sync::mpsc.

Since I would prefer not to install additional crates just to use Rapier, I'd like to suggest using the standard library implementation, unless there is a specific need or feature from crossbeam-channel that Rapier explicitly relies on.