fread() TypeError in TarArchiveWriter.php

Problem/Motivation

Content editing screen fails to load due to fread error in TarArchiveWriter.php The error received is

TypeError: fread(): Argument #1 ($stream) must be of type resource, bool given in ...\modules\backup_migrate\src\Core\Service\TarArchiveWriter.php on line 49 #0

Steps to reproduce

Install Drupal 9 with PHP 8.1.13 then try to edit a content block.

Proposed resolution

Add a type check to variable submissions to allow a better path for script failure.

Remaining tasks

User interface changes

API changes

Data model changes