[copilot-finds] Bug: Fix whenAll([]) hanging orchestration forever

[YunchuWang]

whenAll([]) creates a WhenAllTask that never completes because no children exist to trigger onChildCompleted(). The condition _completedTasks == _tasks.length (0 == 0) inside onChildCompleted is never reached since the method is never called. This causes orchestrations to hang forever when using whenAll with a dynamically generated list that happens to be empty.

Changes:

• WhenAllTask: Immediately complete with [] when given an empty task array
• WhenAnyTask: Throw an error for empty task array (matching .NET behavior)
• RuntimeOrchestrationContext.run(): Handle already-complete initial yielded tasks by calling resume() immediately, enabling the generator to continue

Summary

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[Copilot]

Pull request overview

This PR fixes a bug where whenAll([]) causes orchestrations to hang indefinitely because onChildCompleted() is never called for an empty task array, so the completion condition is never reached.

Changes:

• WhenAllTask: Immediately marks itself as complete with an empty result when constructed with an empty array.
• WhenAnyTask: Throws an error on construction when given an empty array, matching .NET behavior.
• RuntimeOrchestrationContext: Detects already-complete tasks after a yield and calls resume() immediately.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
src/task/when-all-task.ts	Marks WhenAllTask as immediately complete when given an empty task array
src/task/when-any-task.ts	Throws on empty task array in WhenAnyTask constructor
src/worker/runtime-orchestration-context.ts	Resumes generator immediately when the yielded task is already complete
test/orchestration_executor.spec.ts	Adds tests for whenAll([]), whenAll([]) followed by more work, and whenAny([])

[YunchuWang]

pass