Describe the bug

java.lang.IllegalArgumentException: Merged region A1 must contain 2 or more cells
at org.apache.poi.xssf.usermodel.XSSFSheet.addMergedRegion(XSSFSheet.java:338)
at org.apache.poi.xssf.usermodel.XSSFSheet.addMergedRegion(XSSFSheet.java:303)
at com.flowingcode.vaadin.addons.gridexporter.ExcelStreamResourceWriter.createWorkbook(ExcelStreamResourceWriter.java:106)
at com.flowingcode.vaadin.addons.gridexporter.ExcelStreamResourceWriter.accept(ExcelStreamResourceWriter.java:81)
...

Expected behavior

It should be possible to export a one-column grid.

Minimal reproducible example

Grid<Row> grid = new Grid<>();
grid.addColumn(Row::getNumber).setHeader("Number");
GridExporter<Row> exporter = GridExporter.createFor(grid);
grid.setItems(...);

Add-on Version

2.3.3-SNAPSHOT

Vaadin Version

24.3.9

Additional information

No response