Prevent ValueError when no eligible response-create versions exist

[mshsheikh]

Summary

Prevents a potential ValueError in _ResponseCreateSequencer._auto_response_create_target_version() when no eligible pending versions exist.

Problem

The current implementation computes the target version using max(eligible_versions). If eligible_versions is empty, Python raises ValueError: max() arg is an empty sequence, which can cause response sequencing to fail unexpectedly.

Change

Updates the return statement to use the default parameter:

return max(eligible_versions, default=request_version)

Rationale

Using max(..., default=...) is idiomatic Python and cleanly handles empty iterables without adding conditional branches. request_version is a safe fallback that represents the currently reserved request and maintains forward progress. The change only affects the edge case where no eligible versions are found.

Impact

• Prevents ValueError: max() arg is an empty sequence
• Preserves existing sequencing behavior for normal execution paths
• Improves robustness against unexpected state transitions
• Zero breaking changes to public APIs or async flow