postcard_rpc::host_client::IoClosed should implement core::error::Error

[zeenix]

It should be trivial. The only issue is that Error trait was added to core in 1.81. If that's too new of a Rust release to require, then you want to implement std::error::Error when use-std is enabled.

[jamesmunns]

Happy to take a PR for this. We don't have any specific MSRV guarantees, so if it works on current stable I am likely to be fine with that.

[jamesmunns]

Oh, also, fwiw, the host_client parts are currently only intended for std, so implementing either core::error::Error or just std::error::Error should be fine.