NullReferenceException in CopyDxfStylesTables

[PatrickvL]

EPPlus usage

Noncommercial use

Environment

WIndows

Epplus version

7.3.2

Spreadsheet application

No response

Description

Similar to #1597, another NullReferenceException happens when copying sheets from one ExcelPackage to another, using this code:

ExcelPackage.LicenseContext = LicenseContext.NonCommercial;
using ExcelPackage publishedPackage = ExcelPackage new NewExcelPackage(new FileInfo(excelFileName));
// Copy the sheets added to the Complete report up until now.
foreach (ExcelWorksheet completeSheet in workbook.Worksheets)
{
    Logger.Log("    Copying sheet: " + completeSheet.Name);
    // This is significantly faster compared to creating and populating all preceding sheets twice.
    publishedPackage.Workbook.Worksheets.Add(completeSheet.Name, completeSheet);
}

The exception has this call stack:

   at OfficeOpenXml.Core.Worksheet.WorksheetCopyHelper.CopyDxfStylesTables(ExcelWorksheet copy, ExcelWorksheet added)
   at OfficeOpenXml.Core.Worksheet.WorksheetCopyHelper.CopyDxfStyles(ExcelWorksheet copy, ExcelWorksheet added)
   at OfficeOpenXml.Core.Worksheet.WorksheetCopyHelper.CloneCellsAndStyles(ExcelWorksheet Copy, ExcelWorksheet added)
   at OfficeOpenXml.Core.Worksheet.WorksheetCopyHelper.Copy(ExcelWorksheets targetWorksheets, String name, ExcelWorksheet sourceWorksheet)
   at OfficeOpenXml.ExcelWorksheets.Add(String Name, ExcelWorksheet Copy)

This happens on below last line, because excelTable2 is null:

for (int j = 0; j < excelTable.Columns.Count; j++)
{
    ExcelTableColumn excelTableColumn = excelTable.Columns[j];
    ExcelTableColumn excelTableColumn2 = excelTable2.Columns[j]; // <-- NullReferenceException !

The likely reason it becomes null, is because the assignment looks like this: ExcelTable excelTable2 = added.Tables[excelTable.Name]; while the preceding line assign the source like this: ExcelTable excelTable = copy.Tables[i];

So, perhaps merely changing the offending line into this might solve it? ``ExcelTable excelTable2 = added.Tables[i];`