Break loop when channel is closed

[MMitsuha]

When I keep typing on the keyboard and press ESC to exit the program, the program will panic due to channel closure.

[joshka]

I suspect that this is still a bug as the select can complete on either branch of the select in a non-deterministic fashion. The right way to handle (I think) is to not fail when the sender fails to send. The send failing can indicator that the receiver is closed. See https://docs.rs/tokio/latest/tokio/sync/mpsc/struct.Sender.html

I think there's probably a second bug with this in how cancelations are handled https://docs.rs/tokio/latest/tokio/sync/mpsc/struct.Sender.html#cancel-safety