Sorry to reply to my own post, but the more I stare at this, the more I suspect this might not be the bootloader's fault after all. It seems that boot.js for "Health tracking" is flawed. Perhaps someone who is more JS knowledgeable can have a look...
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.
Sorry to reply to my own post, but the more I stare at this, the more I suspect this might not be the bootloader's fault after all. It seems that boot.js for "Health tracking" is flawed. Perhaps someone who is more JS knowledgeable can have a look...