SafeLaunch.kt

Each line, with the release that last changed it.

0.5.0	1	package dev.stave.ui
	2
	3	import androidx.lifecycle.ViewModel
	4	import androidx.lifecycle.viewModelScope
	5	import kotlinx.coroutines.CoroutineExceptionHandler
	6	import kotlinx.coroutines.CoroutineScope
	7	import kotlinx.coroutines.Job
	8	import kotlinx.coroutines.launch
	9
	10	/**
	11	* Coroutine exception handler shared by every ViewModel.launch site.
	12	*
	13	* Without this, uncaught exceptions from viewModelScope.launch bubble up to the JVM
	14	* default handler, which Compose Desktop / Swing surfaces as an opaque "Error"
	15	* dialog showing only the exception message — e.g. `index: 57, size: 57` after a
	16	* right-click → Play Next, with no stack trace and no way to recover gracefully.
	17	*
	18	* Logging here means the same exception becomes a stderr stack trace
	19	* (recoverable from `./gradlew :desktop:run` output or a shell-launched packaged
	20	* install) and the user keeps playing music. The app remains responsive.
	21	*
	22	* Note: This swallows the exception by handling it — viewModelScope's
	23	* SupervisorJob doesn't cancel siblings, so other launches continue normally.
	24	*/
	25	private val viewModelExceptionHandler = CoroutineExceptionHandler { _, throwable ->
	26	System.err.println(
	27	"[Earhorn] ViewModel coroutine threw (${throwable.javaClass.simpleName}):"
	28	)
	29	throwable.printStackTrace(System.err)
	30	}
	31
	32	/**
	33	* Like viewModelScope.launch, but installs [viewModelExceptionHandler] so an
	34	* unexpected throw becomes a logged stack trace rather than an error dialog.
	35	*
	36	* Use for any coroutine triggered by a user action (right-click handlers,
	37	* button clicks, menu items, drag callbacks, etc). Long-running collection
	38	* jobs (state flows, lifecycle observers) can also use this; the handler
	39	* only fires on actually-uncaught exceptions.
	40	*/
	41	fun ViewModel.safeLaunch(block: suspend CoroutineScope.() -> Unit): Job =
	42	viewModelScope.launch(viewModelExceptionHandler, block = block)