Summary

This method finds and returns the first worksheet that exists (not deleted), regardless of its id. Resolves the issue where getWorksheet(1) would fail after deleting the first worksheet.

Problem: When users delete worksheets, the IDs don't get reassigned. So after deleting worksheet with id=1, calling getWorksheet(1) returns undefined even though other worksheets exist.

Solution: The new getFirstWorksheet() method finds the first existing worksheet in the internal array, providing a reliable way to get the first worksheet regardless of deletions.

Test plan

I wrote unit-tests covering all scenarios:

• Returns first worksheet normally
• Returns correct worksheet after single/multiple deletions
• Returns undefined when no worksheets exist

Run with:

npm run test:unit -- spec/unit/doc/workbook.spec.js --grep "getFirstWorksheet"

All tests pass (5/5).