Improved Robustness: Handle Missing Data in submissions.py

[AishwaryJain07]

This PR handles the task of adding proper exception handling in submissions.py when fetching entries from HTTP responses.

• Implemented checks for missing keys (KeyError) in the response data, preventing unexpected program crashes.
• ImportError, RuntimeError: prevents unexpected behavior.
• requests.exceptions.HTTPError , requests.exceptions.RequestException: catches specific exceptions like HTTPError and to handle potential network issues or download failures.
• docker.errors.ImageNotFound.