Make sure that `--no-default-features --features std,defmt` compiles

There are a bunch of places where we do log `std::io::Error` and this cannot work with `defmt`.
We need to hunt those places and wrap the `std::io::Error` variant with `debug2format!` or `display2format!`  as needed.

Perhaps low priority, as I'm not sure running `defmt` on a STD platform is a topic in the first place.