TypeError: Cannot read property 'length' of null

[RashmiRanganathan]

Just tried to write into a file using documentation. Throws error

return this._rowZero + this._rows.length; ^

TypeError: Cannot read property 'length' of null at WorksheetWriter.get _nextRow [as _nextRow]

[linspw]

Try return this._rowZero && this._rows.length;