SaveAs exception after InsertCellsBefore

[BennM666]

• Bug

Version of ClosedXML

0.94.2

What is the current behavior?

If I try to access the last cell of a line and then I insert a cell (even on another line) when I save I have an exception : System.ArgumentOutOfRangeException with 'columnNumber'

Code to reproduce problem:

public void Main()
{
            var wb = new XLWorkbook();
            var ws = wb.AddWorksheet("Feuil1");
            var maxCell = ws.Cell(5, ws.ColumnCount());
            maxCell = null;
            ws.Cell(100, 100).InsertCellsBefore(1);
            wb.SaveAs("testInsert.xlsx");
            wb.Dispose();
}