Guard against PHP 8.0.0 and higher versions: count() throwing fatal error on invalid countable types passed to the value parameter

[alfonso100]

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Describe the bug
A fatal error happens on WP 6.0.2 / PHP 8.1.9 / WPR 3.12.0.5 if the $_GET value is null here:

wp-rocket/inc/Engine/Preload/Subscriber.php

Line 188 in 6e499c2

if ( 0 < count( $_GET ) || ( $this->query->is_pending( $url ) && $this->options->get( 'do_caching_mobile_files', false ) ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended

Per @engahmeds3ed :

According to PHP documentation
8.0.0 count() will now throw TypeError on invalid countable types passed to the value parameter.

this is the error:

Fatal error: Uncaught TypeError: count(): Argument #1 ($value) must be of type
Countable|array, null given in /home/httpd/vhosts/site.com/httpdocs/wpcontent/plugins/wp-rocket/inc/Engine/Preload/Subscriber.php:188 Stack trace: #0
/home/httpd/vhosts/site.com/httpdocs/wp-content/plugins/wprocket/inc/Engine/Preload/Subscriber.php(188): count(NULL) #1
/home/httpd/vhosts/site.com/httpdocs/wp-includes/class-wp-hook.php(307):
WP_Rocket\Engine\Preload\Subscriber->update_cache_row('') #2
/home/httpd/vhosts/site.com/httpdocs/wp-includes/class-wp-hook.php(331): WP_Hook-
>apply_filters('', Array) #3 /home/httpd/vhosts/site.com/httpdocs/wpincludes/plugin.php(476): WP_Hook->do_action(Array) #4
/home/httpd/vhosts/site.com/httpdocs/wp-content/plugins/wprocket/inc/Engine/Optimization/Buffer/Optimization.php(109): do_action('rocket_after_pr...')
#5 [internal function]: WP_Rocket\Engine\Optimization\Buffer\Optimization-
>maybe_process_buffer('...', 9) #6 /home/httpd/vhosts/site.com/httpdocs/wpincludes/functions.php(5275): ob_end_flush() #7
/home/httpd/vhosts/site.com/httpdocs/wp-includes/class-wp-hook.php(307):
wp_ob_end_flush_all('') #8 /home/httpd/vhosts/site.com/httpdocs/wp-includes/class-wphook.php(331): WP_Hook->apply_filters('', Array) #9
/home/httpd/vhosts/site.com/httpdocs/wp-includes/plugin.php(476): WP_Hook-
>do_action(Array) #10 /home/httpd/vhosts/site.com/httpdocs/wp-includes/load.php(1102):
do_action('shutdown') #11 [internal function]: shutdown_action_hook() #12 {main} thrown in
/home/httpd/vhosts/site.com/httpdocs/wp-content/plugins/wprocket/inc/Engine/Preload/Subscriber.php on line 188

To Reproduce
Steps to reproduce the behavior:

1. Empty/unset the $_GET parameter
2. Trigger preload
3. See error

Expected behavior
We should guard against this error.

Additional context
Tickets:
https://secure.helpscout.net/conversation/1997531112/365760?folderId=377611
https://secure.helpscout.net/conversation/2003166039/367167?folderId=273766

Slack thread:
https://wp-media.slack.com/archives/C43T1AYMQ/p1662646309671649

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