fix: reduce verbosity of errors due to string conversion

[wjones127]

• Eliminates cases where we needlessly convert errors to strings.
• Uses DataFusionError::ExecutionJoin() when appropriate.

[github-actions]

Code Review

This PR improves error handling by preserving error context rather than converting to strings. The changes are straightforward and follow existing patterns in the codebase.

P1: Consider using Error::Internal instead of Error::Stop as dummy value

In rust/lance-index/src/vector/ivf/shuffler.rs:

Some(Err(err)) => {
    // Using Error::Stop as dummy value to take the error out.
    return Err(std::mem::replace(err, Error::Stop));
}

While this pattern exists in builder.rs, using Error::Stop (which semantically means "stream early stop") as a placeholder after extracting the real error is a code smell. The value left behind after mem::replace should never be observed, but if it somehow is, Error::Stop could cause confusing behavior compared to Error::Internal { message: "error consumed", .. }.

This is a minor concern since the pattern is already established, but worth noting for future consideration.

All changes look correct

• Using DataFusionError::ExecutionJoin for JoinError is appropriate
• Using DataFusionError::External for Lance errors and DataFusionError::ArrowError for Arrow errors preserves type information
• The ? operator changes correctly leverage existing From implementations
• The empty stream error is now correctly typed as InvalidInput rather than generic IO error

No blocking issues.

[codecov]

Codecov Report

❌ Patch coverage is 11.76471% with 15 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
rust/lance-index/src/vector/ivf/shuffler.rs	9.09%	10 Missing ⚠️
rust/lance/src/io/exec/knn.rs	0.00%	0 Missing and 2 partials ⚠️
rust/lance/src/dataset/scanner.rs	0.00%	0 Missing and 1 partial ⚠️
rust/lance/src/dataset/write/update.rs	0.00%	1 Missing ⚠️
rust/lance/src/io/exec/pushdown_scan.rs	0.00%	1 Missing ⚠️

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