in index.d.ts, Worksheet.dimensions returns array of Range. https://github.com/exceljs/exceljs/blob/e6e12030f475c7360f930bc06f8d686325a89dfe/index.d.ts#L869 but, Worksheet.dimensions returns Range. https://github.com/exceljs/exceljs/blob/e6e12030f475c7360f930bc06f8d686325a89dfe/lib/doc/worksheet.js#L106-L117