If quitting the debugger when stopped at a breakpoint it is not possible to reconnect.
$ dartino debug samples/stm32f746g-discovery/disco-light.dart on tty /dev/ttyACM0
Using template settings file '/tmp/dartino-sdk/internal/.dartino-settings'
Closing tty-connection
Handshake with VM on /dev/ttyACM0 timed out.
If quitting the debugger when stopped at a breakpoint it is not possible to reconnect.