cargo playdate run --device fails silently if the serial connection is in use

[paulyoung]

I ran cargo playdate run --device and got Running <my project> on a device but nothing was happening. After a while I realized that it's because something was already using the serial connection.

[paulyoung]

This was with cargo-playdate 0.5.0-beta.4

[paulyoung]

Still an issue on 0.5.0

[boozook]

Hmmm 🤔, is it something new or regression? Is it was so in cargo-playdate v0.4.x?

Note, we can't use connection to device that already opened exclusively for other process. It could work with .cu/tty serial-port-fd but not recommended because one process can break it for another.

[boozook]

Okay, we need good errors for that part of the system.
rel.: #359