Or https://stackoverflow.com/questions/35977468/nodejs-serialport-setcommstate which implies there aren't drivers for the serial port chip you're using. Are you able to connect with a terminal app like Putty?
@Gordon started
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
Or https://stackoverflow.com/questions/35977468/nodejs-serialport-setcommstate which implies there aren't drivers for the serial port chip you're using. Are you able to connect with a terminal app like Putty?