🤖 Fix IndexError when accessing empty list in get_default_owner

[seer-by-sentry]

👋 Hi there! This PR was automatically generated 🤖

Triggered by michael.sun@sentry.io

Fixes SENTRY-2M00

The function get_default_owner in src/sentry/models/organization.py attempts to access the first element of a potentially empty list returned by get_owners(). This causes an IndexError when the list is empty. The plan involves modifying get_default_owner to handle the case where get_owners() returns an empty list, preventing the IndexError.

The steps that were performed:

1. Handle empty owner list in get_default_owner

📣 Instructions for the reviewer which is you, yes you:

• If these changes were incorrect, please close this PR and comment explaining why.
• If these changes were incomplete, please continue working on this PR then merge it.
• If you are feeling confident in my changes, please merge this PR.

This will greatly help us improve the autofix system. Thank you! 🙏

If there are any questions, please reach out to the AI/ML Team on #proj-autofix

🤓 Stats for the nerds:

Prompt tokens: 12257
Completion tokens: 1119
Total tokens: 13376

[getsantry]

This pull request has gone three weeks without activity. In another week, I will close it.

But! If you comment or otherwise update it, I will reset the clock, and if you add the label WIP, I will leave it alone unless WIP is removed ... forever!

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"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀