Problem happens on old and new Web IDE for me too.
BTW, flashing works fine at high speed in both versions.
Throttle makes flashing horibbly slow, 30 minutes instead of seconds.
So I take the same way Sacha does.
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.
Problem happens on old and new Web IDE for me too.
BTW, flashing works fine at high speed in both versions.
Throttle makes flashing horibbly slow, 30 minutes instead of seconds.
So I take the same way Sacha does.