fix: Add error handling for Excel SaveAs operation in Convert-Files function

SharePointFunctions.ps1

@@ -482,9 +482,15 @@ function Convert-Files {
                     $workbook = $excel.Workbooks.Open($downloadPath)
                     
                     Write-Host "Saving as XLSX: $xlsxPath"
-                    # Save directly to the final path
-                    $workbook.SaveAs([string]$xlsxPath, 51)  # 51 = xlWorkbookDefault (xlsx format)
-                    $workbook.Close($true)
+                    try {
+                        # Save directly to the final path
+                        $workbook.SaveAs([string]$xlsxPath, 51)  # 51 = xlWorkbookDefault (xlsx format)
+                        $workbook.Close($true)
+                    }
+                    catch {
+                        $script:txtStatus.Text += "Error during SaveAs: $($_.Exception.Message)`n"
+                        throw "SaveAs failed: $($_.Exception.Message)"  # Re-throw the exception to be caught by the outer catch
+                    }
                     
                     Start-Sleep -Seconds 2  # Give Excel time to finish