Error handling when not connected (Flash Red LED by default)

[gfwilliams]

Add flags (E.setFlags) for:

• Flashing Red LED when there's an uncaught error (default on devices with physical LED)
• Writing the Error to Storage (not default)

Which should help catch errors that occur when nothing is connected to the device

[gfwilliams]

... maybe store the error in RAM by default (it can be deleted if more memory is needed like we do for history) and set something in E.getErrorFlags. Then when the Web IDE connects it can check the error flags and output the exception that occurred when nothing was connected

[gfwilliams]

I decided to make saving to Storage the default. It now only saves an error if E.setFlags({noErrorSave:true}) isn't set and if there isn't already a file called ERROR so this won't cause increased storage wear or anything.

[gfwilliams]

Any thoughts about flashing the red LED?

• enabled by default
• 3 quick red flashes on uncaught error
• flag to disable?

This feels like a useful addition, especially on Puck.js where things like advertising errors can happen only when disconnected - but is it likely someone will complain?

[gfwilliams]

@bobrippling as you're looking into the stack trace stuff, what are your thoughts on saving errors to storage?

I've had it on devices I'm developing with for a few days now and I'm finding it kind of annoying. Although potentially it could be quite interesting for Bangle.js users if there's some support added to the app loader I guess.

I guess other options are:

• enable it only if the bluetooth console isn't connected.
• make the error detected prompt smaller and less annoying
• just make it a flag that can be enabled (but then normal users don't get to use it)
• just store to RAM only so the IDE can query it when it connects

[bobrippling]

I've done a bit before, namely espruino/BangleApps#3634 (comment), which was useful but to be honest, I run into so few errors that I don't really need it regularly.

Which I suppose is a plus for saving to storage (if it were regularly, I'd go for your storing to RAM idea). I think the bluetooth console check sounds good still - what is it about the process you find annoying? The IDE functionality?

[gfwilliams]

what is it about the process you find annoying?

When developing I usually upload as I make changes, and I always make mistakes so it's pretty much guaranteed I end up with that An Uncaught Error has been saved to Storage message that I then have to remove.

While I stopped it recording errors from code entered at the REPL, on Bangle.js at least you generally upload apps to storage and run from storage, so Bangle.js can't really differentiate between:

• running an app you just uploaded while developing
• running an app while connected to Gadgetbridge, when you might want to log an error

Folks have a habit of complaining whenever something changes, so I guess maybe for now it's worth putting it behind a flag (we can enable it by default in Bangle.js boot code and then see if there are complaints, and maybe enable it by default later?)

[bobrippling]

I get you - I suppose we could have an option so we can write to storage or RAM, then for regular development it's stashed in some RAM variable? But yes - behind a flag sounds nice, enabled by default I suppose for storage is ok since it won't write if there's already a file there, like you say