Undefined index with IReader::load method

[kalyabin]

This is:

- [ *] a bug report
- [ ] a feature request
- [ ] **not** a usage question (ask them on https://stackoverflow.com/questions/tagged/phpspreadsheet or https://gitter.im/PHPOffice/PhpSpreadsheet)

What is the expected behavior?

Got exception when create Spreadsheet instance using IReader::load method:

[2020-09-22 22:43:37] local.ERROR: Undefined index: rId7 {"exception":"[object] (ErrorException(code: 0): Undefined index: rId7 at /var/www/vendor/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php:44)
[stacktrace]
#0 /var/www/vendor/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php(44): Illuminate\\Foundation\\Bootstrap\\HandleExceptions->handleError(8, 'Undefined index...', '/var/www/vendor...', 44, Array)
#1 /var/www/vendor/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xlsx/Hyperlinks.php(32): PhpOffice\\PhpSpreadsheet\\Reader\\Xlsx\\Hyperlinks->setHyperlink(Object(SimpleXMLElement), Object(PhpOffice\\PhpSpreadsheet\\Worksheet\\Worksheet))
#2 /var/www/vendor/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Reader/Xlsx.php(820): PhpOffice\\PhpSpreadsheet\\Reader\\Xlsx\\Hyperlinks->setHyperlinks(Object(SimpleXMLElement))
...

xlsx file is valid and currently opened.

What is the current behavior?

Correctly created Spreadsheet instance.

What are the steps to reproduce?

Please provide a Minimal, Complete, and Verifiable example of code that exhibits the issue without relying on an external Excel file or a web server:

<?php

require __DIR__ . '/vendor/autoload.php';

$reader = IOFactory::createReaderForFile('path/to/file.xlsx');

$spreadsheet = $reader->load('path/to/file.xlsx');

Which versions of PhpSpreadsheet and PHP are affected?

1.14.1