Fixing the Uncaught TypeError in ListingRepository.php when using PHP 8

[shapeyourbits]

Uncaught TypeError: Cannot access offset of type string on string in /wp-content/plugins/wp-nested-pages/app/Entities/Listing/ListingRepository.php

[shapeyourbits]

Fatal Error using PHP 8.

Uncaught TypeError: Cannot access offset of type string on string in /home/wpsitedirectory/wp-content/plugins/wp-nested-pages/app/Entities/Listing/ListingRepository.php:40

Stack trace:
#0 /home/wpsitedirectory/wp-content/plugins/wp-nested-pages/app/Entities/Listing/Listing.php(317): NestedPages\Entities\Listing\ListingRepository->visiblePages('page')
#1 /home/wpsitedirectory/wp-content/plugins/wp-nested-pages/app/Entities/Listing/Listing.php(392): NestedPages\Entities\Listing\Listing->listOpening(Array, 0)
#2 /home/wpsitedirectory/wp-content/plugins/wp-nested-pages/app/Entities/Listing/Listing.php(369): NestedPages\Entities\Listing\Listing->listPostLevel()
#3 /home/wpsitedirectory/wp-content/plugins/wp-nested-pages/app/Views/listing.php(98): NestedPages\Entities\Listing\Listing->getPosts()
#4 /home/wpsitedirectory/wp-content/plugins/wp-nested-pages/app/Entities/Listing/Listing.php(280): include('/home/wpsi...')
#5 /home/wpsitedirectory/wp-includes/class-wp-hook.php(308): NestedPages\Entities\Listing\Listing->listPosts('')
#6 /home/wpsitedirectory/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters('', Array)
#7 /home/wpsitedirectory/wp-includes/plugin.php(517): WP_Hook->do_action(Array)
#8 /home/wpsitedirectory/wp-admin/admin.php(259): do_action('pages_page_nest...')
#9 /home/wpsitedirectory/wp-admin/edit.php(10): require_once('/home/wpsi...')
#10 {main} thrown in /home/wpsitedirectory/wp-content/plugins/wp-nested-pages/app/Entities/Listing/ListingRepository.php on line 40

changed line 40 from

if ( !$visible || !isset($visible[$post_type]) ) $visible[$post_type] = [];
to

if ( !$visible || !isset($visible[$post_type]) ) {
	$visible= array();
	$visible[$post_type] = [];
}

I should note, I didn't actively seek out any other errors, with this small change the plugin began to function.

[PLUS-RobertEhrenleitner]

The original thing did not work because in PHP 8 it is no longer allowed to add array values to an uninitialized variable. However, you could do it in one command:

if ( !$visible || !isset($visible[$post_type]) ) $visible = [$post_type => []];

Anyway, your fix is perfect.