I am hoping to track any errors that happen on my kobweb site, but there are two problems: 1. try/ca...

# kobweb

[jeff]

I am hoping to track any errors that happen on my kobweb site, but there are two problems:
1. try/catch is not allowed inside @Composables
2. JS window.onerror isn't being triggered, even if I do something like null!!. I do see an error message in the js console, with a kotlin-js stack trace, but maybe kotlin isn't propagating it all the way up?
Anyone run into this? Any suggestions?

[David Herman]

I haven't tried this before so I'll double check I'm not screwing something up. But I assume composables run on their own thread (since they are being dispatched as needed by the compose engine) which would make throwing exceptions tricky.

[David Herman]

It's weird. I installed a window.onerror listener and added this fake crash:

TextInput(name, onTextChanged = { name = it; error("onTextChanged") })

and that got handled.

Then, in the same page, I added a LaunchedEffect crash:

...
LaunchedEffect(Unit) { error("LaunchedEffect") }
var name by remember { mutableStateOf("") }
TextInput(name, onTextChanged = { name = it; error("onTextChanged") })
...

and in that case, both crashes were uncaught and NOT handled by window.onerror. I don't know what's going on.

[David Herman]

I have no idea how feasible this is but you can write javascript to overwrite the console.log call: https://stackoverflow.com/questions/9216441/intercept-calls-to-console-log-in-chrome

I wonder if you can intercept console.error messages this way...

[David Herman]

This definitely looks like a pain point in general in web after doing a bit of search, but unfortunately I don't know much

[jeff]

Iiiinteresting... Worth a shot!

[CLOVIS]

I believe you'll have to insert a try-catch into all effects (LaunchedEffect, SideEffect, event handlers…). If an exception reaches the Compose Runtime, it crashes and everything dies.