[otlib,qemu,usb] Ignore errors coming from shutting down the host thread

Signed-off-by: Amaury Pouly <[email protected]>

Author: pamaury

sw/host/opentitanlib/src/transport/qemu/usbdev.rs

@@ -899,7 +899,12 @@ impl QemuHostThread {
             if let Err(res) =
                 Self::host_qemu_reader_thread(usbdev_for_reader, channel_send_for_reader)
             {
-                log::error!("QEMU reader failed with error: {res:?}");
+                // Ignore errors coming for the mpsc channel because they indicate that
+                // the host thread shut down and the reader couldn't send a message.
+                match res.downcast::<mpsc::SendError<HostChannelEvent>>() {
+                    Ok(_) => (),
+                    Err(err) => log::error!("QEMU reader failed with error: {err:?}"),
+                }
             }
         });