fix: Correct off-by-one error in CsvRow#getCell(int)

[bengbengbalabalabeng]

Purpose of the pull request

Fixed: #676.

What's changed?

• Corrected the 0-based indexing logic in CsvRow#getCell(int).
• Add unit test.

Checklist

• I have read the Contributor Guide.
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

[bengbengbalabalabeng]

PTAL 😁 @delei

[psxjoy]

Please handle conflict files :)

[bengbengbalabalabeng]

Please handle conflict files :)

Thanks for the feedback! I've resolved the conflict files. 😁

[psxjoy]

Let's run unit-test first:)

[bengbengbalabalabeng]

Let's run unit-test first:)

All existing CsvRowTest cases passed.
Should I add more coverage, or is there another concern?