The App Loader on the other hand should do this already I think, so I wonder why it didn't in your case. I guess maybe it was thrown off by the Gadgetbridge JSON being sent?
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.
I added it to the wiki at https://github.com/espruino/BangleApps/wiki#faq-frequently-asked-questions
I will investigate into this.