PhpSpreadsheet Notice: Undefined offset: 4 - phpspreadsheet

Question

I have been struggling with finding a way to read excel files in a directory, copy the worksheet called "Division" into a new file, then number the new worksheets increment by one - Division1, Division2, etc...
The following is my code, which I am receiving a warning for undefined index, which is not a big deal, but it only creates a new excel file with only four worksheets, when there should be over 240 worksheets.
ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);
use PhpOffice\PhpSpreadsheet\Helper\Sample;
use PhpOffice\PhpSpreadsheet\IOFactory;
$exportedFiles = scandir('PhpSpreadsheet/Export');
$inputFileNames = [];
$sheetnames = [];
$outfile = 'all-together-now.xlsx';
foreach($exportedFiles as $key=> $value) {
if ($value == '.' || $value == '..') {
} else {
array_push($inputFileNames, 'PhpSpreadsheet/Export/' . $value);
array_push($sheetnames, 'Division');
}
}
$inputFileType = 'Xlsx';
$reader = IOFactory::createReader($inputFileType);
$reader->setLoadSheetsOnly($sheetnames);
$contador = 1;
foreach ($inputFileNames as $book => $inputFileName) {
echo ('$inputFileName: ' . $inputFileName) . '</br>';
$reader = IOFactory::createReader("Xlsx");
$spreadsheet = $reader->load($inputFileName);
$clonedWorksheet = clone $spreadsheet->getSheetByName('Division');
$clonedWorksheet->setTitle('Division' . $contador);
$spreadsheetMain = $reader->load($outfile);
$spreadsheetMain->addSheet($clonedWorksheet);
$writer = IOFactory::createWriter($spreadsheetMain, "Xlsx");
$writer->save($outfile);
$contador++;
}
The following are the warning notices:
Notice: Undefined offset: 4 in
PhpOffice\PhpSpreadsheet\Writer\Xlsx->save( )
PhpOffice\PhpSpreadsheet\Spreadsheet->garbageCollect( )
As usual, thanks in advance

Answer 1

Part of the solution was bumping up the memory and the other was to use addSheet()
The following is the code that works:
ini_set('memory_limit','32768M');
use PhpOffice\PhpSpreadsheet\IOFactory;
require_once 'PhpSpreadsheet/src/Bootstrap.php';
$exportedFiles = scandir('PhpSpreadsheet/Export');
$inputFileNames = [];
$sheetnames = [];
$outfile = 'all-together-now.xlsx';
foreach($exportedFiles as $key=> $value) {
if ($value == '.' || $value == '..') {
} else {
array_push($inputFileNames, 'PhpSpreadsheet/Export/' . $value);
array_push($sheetnames, 'Division');
}
}
$inputFileType = 'Xlsx';
$reader = IOFactory::createReader($inputFileType);
$reader->setLoadSheetsOnly($sheetnames);
$contador = 1;
foreach ($inputFileNames as $book => $inputFileName) {
echo ('$inputFileName: ' . $inputFileName) . '</br>';
$reader = IOFactory::createReader("Xlsx");
$spreadsheet = $reader->load($inputFileName);
$spreadsheet->getSheetByName('Division')->getStyle('Division');
$clonedWorksheet = clone $spreadsheet->getSheetByName('Division');
$clonedWorksheet->setTitle('Division' . $contador);
/* open new file for writing spread sheets to it */
$spreadsheetMain = $reader->load($outfile);
$spreadsheetMain->addSheet($clonedWorksheet);
$writer = IOFactory::createWriter($spreadsheetMain, "Xlsx");
$writer->save($outfile);
$contador++;
}
$spreadsheet->disconnectWorksheets();
echo "The process has completed";
die();
The aforementioned script created an excel workbook with 247 worksheets from the 247 excel files