save() breaks my pico - I have to do a firmware flash...

Are you doing something to do with Graphics?

I've discovered a crash caused by initialising the Graphics library twice (it seems to be a recent regression). Hopefully I'll get a fix out tomorrow.

However, the way to make it work for now is to make sure that there's no call to onInit() in the code that you upload. Then, you can call save(), and when the save is done Espruino will restart and will automatically call onInit() itself.