You could connect with the Web IDE and then if if happens you should hopefully be able to see in the console what the full error message is
Maybe you could add console output to https://banglejs.com/apps/ - the "More .." tab? that way it could be seen also in the web view version included inside gadgetbridge. And BTW that one is great and mostly works. There are issues with custom install dialogs (like firmware upgrade, watchface font selection) - buttons do not work, and sometimes GB is confused with the extra traffic done by app installation but otherwise it is quite usable - app updates without dialogs work quite well.
Yes - sadly I am not a graphic designer, and getting the app sorted took priority over the icon - but if anyone is reading this and wants to contribute something better I'd be happy to include it ;)
I did a quick google and all I saw was https://www.ebay.co.uk/itm/394096073676 which looks kind of similar. Do you have a link?
In the Settings for the Messages app there is an option called
Unlock Watch- if enabled this will light the screen up I think, but it does also unlock the screen too.
Yes, it's a good point. A page on this for Bangle.js would be good. If Bluetooth is off you're totally fine, or you can also turn 'Programmable' off in settings in which case even if someone did connect to the Bangle the worst they could do is send you notifications - they can't change the code that's on it or anything like that.
The syntax error toast could actually be because of some app that's installed on the Bangle that has a problem. You could connect with the Web IDE and then if if happens you should hopefully be able to see in the console what the full error message is (or you could look in the Gadgetbridge debug logs)
Hope that's some help!