ErrorTextField.kt

Box(
    modifier = Modifier
        .requiredHeight(16.dp)
        .padding(start = 16.dp, end = 12.dp)
) {
    CompositionLocalProvider(
        LocalTextStyle provides LocalTextStyle.current.copy(
            fontSize = 12.sp,
            color = if (isError) MaterialTheme.colors.error else LocalTextStyle.current.color
        )
    ) {
        if (isError) {
            if (errorMessage != null) {
                errorMessage()
            }
        } else {
            if (helperMessage != null) {
                CompositionLocalProvider(
                    LocalContentAlpha provides ContentAlpha.medium
                ) {
                    helperMessage()
                }
            }
        }
    }
}