Strip away undefined points in series

[salunn]

We are trying to export data displayed in Highcharts as an Excel spreadsheet using export-csv.js library. A problem arises when your series is not displayed in its entirety on the chart. In that scenario, the resulting excel will display 'undefined' as values for the data on y-axis, because it was not shown on the active chart area.

As far as my colleagues and I understand the inner workings of Highcharts, the functionality where datapoints in series outside of the active chart area are undefined could be considered core and really hard to change. Therefore, would it be possible to instead strip away the undefined datarows from the resulting excel?