Fix renderSingleTask error swallowing on sequential calls

The setImmediate deferral of unmountInk() introduced a race condition
when renderSingleTask is called sequentially: the first instance's
deferred unmountInk() can fire after the second instance starts,
causing the second waitUntilExit() to resolve prematurely. If the
second task then throws, the error is silently swallowed because
render().catch(reject) never fires.

Fix: add onError callback to SingleTask (mirroring onComplete) so
errors are propagated directly via the callback rather than relying
on waitUntilExit() rejection, which is unreliable across sequential
ink renders.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: nickwesselman

packages/cli-kit/src/private/node/ui/components/SingleTask.tsx

@@ -9,11 +9,12 @@ interface SingleTaskProps<T> {
   title: TokenizedString
   task: (updateStatus: (status: TokenizedString) => void) => Promise<T>
   onComplete?: (result: T) => void
+  onError?: (error: Error) => void
   onAbort?: () => void
   noColor?: boolean
 }
 
-const SingleTask = <T,>({task, title, onComplete, onAbort, noColor}: SingleTaskProps<T>) => {
+const SingleTask = <T,>({task, title, onComplete, onError, onAbort, noColor}: SingleTaskProps<T>) => {
   const [status, setStatus] = useState(title)
   const [isDone, setIsDone] = useState(false)
   const {exit: unmountInk} = useApp()
@@ -41,9 +42,10 @@ const SingleTask = <T,>({task, title, onComplete, onAbort, noColor}: SingleTaskP
       })
       .catch((error) => {
         setIsDone(true)
+        onError?.(error)
         setImmediate(() => unmountInk(error))
       })
-  }, [task, unmountInk, onComplete])
+  }, [task, unmountInk, onComplete, onError])
 
   if (isDone) {
     // clear things once done

packages/cli-kit/src/public/node/ui.tsx

@@ -522,7 +522,7 @@ export async function renderSingleTask<T>({
   renderOptions,
 }: RenderSingleTaskOptions<T>): Promise<T> {
   return new Promise<T>((resolve, reject) => {
-    render(<SingleTask title={title} task={task} onComplete={resolve} onAbort={onAbort} />, {
+    render(<SingleTask title={title} task={task} onComplete={resolve} onError={reject} onAbort={onAbort} />, {
       ...renderOptions,
       exitOnCtrlC: false,
     }).catch(reject)