refactor: assume we have exactly one candidate

[andylolz]

Fixes #145.

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Pull request checklist

• [x] I have linked my PR to an issue
• [x] I’ve used conventional commits
• [x] My branch is up-to-date with main
• [x] Where appropriate, I have added or updated tests
• [ ] Where appropriate, I have updated documentation to reflect my changes

[andylolz]

Thanks for reviewing 🙏🏻