XLSX to Markdown conversion to work with XLSX files with empty Sheets.

[tiblu]

XLSX to Markdown conversion to work with XLSX files with empty Sheets.

The problem

IF you tried to convert an XLSX file containing empty Sheets, following error would occur:

console.error
    TypeError: Cannot read properties of undefined (reading 'indexOf')
        at decode_range (/home/tiblu/dev/kaiq-api/node_modules/xlsx/xlsx.js:4118:18)
        at Object.sheet_to_html (/home/tiblu/dev/kaiq-api/node_modules/xlsx/xlsx.js:20905:10)
        at XlsxConverter.convert (/home/tiblu/dev/kaiq-api/node_modules/markitdown-ts/dist/index.cjs:715:49)
        at processTicksAndRejections (node:internal/process/task_queues:105:5)
        at MarkItDown._convert (/home/tiblu/dev/kaiq-api/node_modules/markitdown-ts/dist/index.cjs:1149:17)
        at MarkItDown.convert_local (/home/tiblu/dev/kaiq-api/node_modules/markitdown-ts/dist/index.cjs:1136:12)

The fix

Check that ws["!ref"] is defined so that the XLSX library would not fail.
That said, it MAY be right to fix it somehow inside the XLSX library, BUT seeing how many un-merged PR-s the repo has, I abandoned all hope and decided to fix it inside this codebase.

Sidenotes

Thanks for the tool, nice to contribute to a OSS project with easy setup and good test coverage.

[tiblu]

Thanks for merge!
Any plans for a release to NPM?
Due to the nature of this project, using it from my own it is not possible to use a link to my Git fork as dependency in package.json.