pub fn stderr() -> Result<Arc<dyn ImmutableWrite>, &'static str>Expand description
Applications call this function to acquire a writer to its stderr queue.
Errors can occur in two cases. One is when it fails to get the task_id of the calling task, and the second is that there’s no stderr writer stored in the map. Shells should make sure to store IoStreams for the newly spawned app first, and then unblocks the app to let it run.