Using Compose MPP 1.4.0, is anyone else experiencing random crashes with a javascript console error ...

# compose-web

[Mike Digman]

Using Compose MPP 1.4.0, is anyone else experiencing random crashes with a javascript console error in skiko of caught RuntimeError: remainder by zero at skiko.wasm:0x28a295? From what I can tell, there may be a low-level math bug somewhere related to shadow rendering?

[Mike Digman]

I've managed to trace down one cause of this to a rather specific shadow modifier:

.shadow(elevation = 2.dp, shape = RoundedCornerShape(topStart = 28.dp, topEnd = 28.dp))

Different elevation values don't trigger the crash. However, different shape values do. For example, this runs without an issue:

.shadow(elevation = 2.dp, shape = RoundedCornerShape(8.dp))

[Dima Avdeev]

Thanks!
We already made a sample to reproduce this bug here:
https://github.com/JetBrains/compose-multiplatform-core/blob/30150346d8c4c04c6a17e[…]Main/kotlin/androidx/compose/mpp/demo/RoundedCornerCrashOnJS.kt

[Dima Avdeev]

We will fix it

[Oleksandr Karpovich [JB]]

a ticket to follow - https://github.com/JetBrains/compose-multiplatform/issues/3072

[Mike Digman]

Thanks folks! Subscribed to the bug. I may have found another circumstance that triggers this bug outside of corner rounding. If I can isolate it, I'll be sure to let you know.

[Mike Digman]

Ah, I found it. This time I'm getting a similar wasm error but it's not related to the shape. The following code runs without issue of scaleX = scaleY, otherwise it crashes but only in JS - works fine on Desktop and Android.

@Composable
fun AsymmetricScaleTester() {
    Box(
        Modifier.size(100.dp)
            .graphicsLayer(scaleX = 0.7f, scaleY = 1f)
            .shadow(elevation = 2.dp)
    )
}

The error is a divide by zero (vs the prior remainder by zero):

skiko.wasm:0x28ab10 Uncaught RuntimeError: divide by zero
    at skiko.wasm:0x28ab10

[Mike Digman]

@Dima Avdeev @Oleksandr Karpovich [JB], filed a bug on this for you with more context: https://github.com/JetBrains/compose-multiplatform/issues/3075

[Chris Sinco [G]]

Are these issues resolved in 1.4.1? I’m seeing a similar crash now in skiko but for Modifier.rotate. But I have a feeling it’s not that. Is there a way to isolate what is causing Skiko crashes? Try/catches and println debugging doesn’t seem to be working initially.

[Oleksandr Karpovich [JB]]

Yes, the issue above is fixed in 1.4.1 So Modifier.rotate is probably different. Is it also "divide by zero" exception?

[Chris Sinco [G]]

“Remainder by zero” - but I don’t actually think it’s rotate so trying to see how I can debug it properly to help

[Chris Sinco [G]]

Right now it’s just a blind skiko runtime exception

[Chris Sinco [G]]

Actually I’ve isolated it to chaining rotate and shadow - here’s the Composable that repros a divide by zero exception

@Composable
fun SimpleView() {
    Box(
        modifier = Modifier
            .size(width = 360.dp, height = 360.dp)
            .rotate(-60.0f)
            .padding(42.dp)
            .shadow(elevation = 16.dp, shape = RoundedCornerShape(size = 32.dp))
            .background(color = Color.Yellow, shape = RoundedCornerShape(size = 32.dp))
    ) { }
}

[Oleksandr Karpovich [JB]]

https://github.com/JetBrains/compose-multiplatform/issues/3299