Hello, sadly i cannot use this Add On. It throws a NullPointerException: I

Directory Exporter
1

Hello, sadly i cannot use this Add On. It throws a NullPointerException:

I Am using Vaadin 14 in compatibility Mode

Caused by: java.lang.NullPointerException
	at org.vaadin.haijian.FileBuilder.<init>(FileBuilder.java:34)
	at org.vaadin.haijian.ExcelFileBuilder.<init>(ExcelFileBuilder.java:24)
	at org.vaadin.haijian.XlsxFileBuilder.<init>(XlsxFileBuilder.java:11)
	at org.vaadin.haijian.Exporter.exportAsExcel(Exporter.java:11)
	at vaadin.MainView.assembleView(MainView.java:210)
	at vaadin.MainView.postConstruct(MainView.java:150)
	... 69 more
2

From the stack trace, looks like the grid is null? Maybe put a break pointer there in the MainView postConstruct() method to see if the grid is constructed correctly?