rendering a chart throws null pointer exception

Steps to Reproduce

1. load the attached file with 5.8.0.FL.20210811-Eval

Current Result

java.lang.NullPointerException
at io.keikaiex.util.HighchartsAxisHelper.drawAxis(HighchartsAxisHelper.java:114)
at io.keikaiex.util.HighchartsHelper.drawChartInner(HighchartsHelper.java:150)
at io.keikaiex.util.HighchartsHelper.drawCharts(HighchartsHelper.java:116)
at io.keikaiex.ui.widget.ChartsWidget.initChart(ChartsWidget.java:138)
at io.keikaiex.ui.widget.ChartsWidget.invalidate(ChartsWidget.java:128)
at io.keikaiex.ui.widget.DefaultWidgetHandler.onLoadWidgetOnDemand(DefaultWidgetHandler.java:170)
at io.keikaiex.ui.widget.DefaultWidgetHandler.onLoadOnDemand(DefaultWidgetHandler.java:150)
at io.keikai.ui.SpreadsheetCtrlImpl.setLoadedRect(SpreadsheetCtrlImpl.java:200)
at io.keikai.ui.au.in.BlockSyncCommand.process(BlockSyncCommand.java:74)
at io.keikai.ui.Spreadsheet.service(Spreadsheet.java:3371)

Expected Result

no error

Debug Information

• 5.7.0 doesn't have this error. Only happen in 5.8.0 FL