Fix undefined value in tsvToJson

[kintsoogi]

Describe what your pull request addresses

• [ ] Adding a TSV to the end of a book would throw errors after trying to edit (GEdit #592)

Test Instructions

• [ ] Open Deply Preview
• [ ] Navigate to the very last verse in a book.
• [ ] In translation notes, navigate to the very last item by using the right arrow button.
• [ ] Add a new EMPTY tsv item (at current reference). Make sure not to put anything in the note field!
• [ ] In the newly created note, edit all of the fields and make sure the changes are reflected.
  • [ ] Verify that no major errors have been thrown
  • [ ] Clicking delete, verify that the note information is shown in the delete dialog