Third party 'espruino-cli' tool is dead...

Ok, I got confused - this is about gzip's espruino-cli after all. I have similar problems when installing it and I think it's to do with espruino-cli using an out of date serialport module (1.2.5) when we're up to at least version 4.0 now.

Try sudo npm install -g espruino and use the espruino tool and not espruino-cli. That's the one I actually maintain, and contains a whole bunch of extra features. It's basically got all the Web IDE's backend packaged into a CLI.