Interactive Task Type Reports Zero Score on Controller Failures #1732

Description In the new Interactive task type, a controller that exits unsuccessfully with empty stderr can produce a successful evaluation worth zero points, instead of being classified as a judging failure. (success=true in interactive_keeper.py)

Steps to reproduce:
Have the controller call exit(1) without writing to stderr, while the contestant program exits normally.

Expected: Internal judging failure (success=False), with no contestant score recorded.

Actual: Successful evaluation (success=True) with zero points and the message “Controller failed”.

My agent suggests the following fixes:

• Treat evaluation_success_mgr=False as a judging failure: success=False, no contestant score.
• Reject a missing score when otherwise accepting the controller’s result.
• Preserve the controller’s diagnostic message for administrators.

Thanks for looking into this!