App freezes if there is a connection problem

[laurentopia]

For example with the maix bit it happens very often that the board doesn't respond to save load if the python script dies. In such case, loading or saving a file from the board freezes upyloader.
The common thing that is expected of a putty type app is that it times out after a few seconds.

[BetaRavener]

There are actually timeouts in place, e.g. https://github.com/BetaRavener/uPyLoader/blob/master/src/connection/serial_connection.py#L258. I'm aware though that there are some freezes in configurations that I haven't been able to debug, that's also the reason for big header in readme. I would need you to dig around with debugger and find out at least place where it freezes waiting (should be easy to get stack trace), if not the cause. But it requires some skills with desktop python development.