ARROW-18247: [JS] fix: RangeError crash in Vector.toArray()

[sarfata]

This fixes a bug which happens when a Vector has been created with multiple data blobs and at least one of them has been padded.

See https://observablehq.com/d/14488c116b338560 for a reproduction of the error and more details.

[github-actions]

Thanks for opening a pull request!

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Then could you also rename pull request title in the following format?

ARROW-${JIRA_ID}: [${COMPONENT}] ${SUMMARY}

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See also:

• Other pull requests
• Contribution Guidelines - How to contribute patches

[github-actions]

https://issues.apache.org/jira/browse/ARROW-18247

[github-actions]

⚠️ Ticket has not been started in JIRA, please click 'Start Progress'.

[domoritz]

Thank you for the pull request. Please add a unit test so we make sure this issue doesn't surface again.

[trxcllnt]

Nice catch, thanks for the fix @sarfata!

[sarfata]

@domoritz @trxcllnt Thanks for your reviews.

I have added a unit test for my scenario. I also realized that my fix did not work when stride is not 1 so I have added a test (and fix) for that too.

I believe one of you will need to approve running the test workflow again before merging.

[domoritz]

Looks like a test is failing.

[sarfata]

@domoritz fixed.

🤦 I did some last minute cleanup and added this test to show exactly the key condition for this bug but ended up with a failing test. Sorry about this.