refactor(sink): Use error instead of unwrap

[xxhZs]

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What's changed and what's your intention?

Replace unnecessary panic with error

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added test labels as necessary. See details.
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
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Documentation

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Release note

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[wenym1]

LGTM