500 Error when generating static site on Multisite

[pjohanneson]

When trying to generate a static site on my locally-hosted WordPress Multisite installation, I consistently hit a 500 error. Examining the WordPress debug log, I saw this:

[28-Feb-2024 22:16:34 UTC] PHP Fatal error:  Uncaught TypeError: array_keys(): Argument #1 ($array) must be of type array, bool given in /srv/www/vhosts/my_site/wp-content/plugins/wp2static/src/DetectPluginAssets.php:42
Stack trace:
#0 /srv/www/vhosts/my_site/wp-content/plugins/wp2static/src/DetectPluginAssets.php(42): array_keys()
#1 /srv/www/vhosts/my_site/wp-content/plugins/wp2static/src/URLDetector.php(119): WP2Static\DetectPluginAssets::detect()
#2 /srv/www/vhosts/my_site/wp-content/plugins/wp2static/src/URLDetector.php(196): WP2Static\URLDetector::detectURLs()
#3 /srv/www/vhosts/my_site/wp-content/plugins/wp2static/src/Controller.php(699): WP2Static\URLDetector::enqueueURLs()
#4 /srv/www/vhosts/my_site/wp-content/plugins/wp2static/src/Controller.php(811): WP2Static\Controller::wp2staticHeadless()
#5 /srv/www/vhosts/my_site/wp-includes/class-wp-hook.php(306): WP2Static\Controller::wp2staticRun()
#6 /srv/www/vhosts/my_site/wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters()
#7 /srv/www/vhosts/my_site/wp-includes/plugin.php(517): WP_Hook->do_action()
#8 /srv/www/vhosts/my_site/wp-admin/admin-ajax.php(188): do_action()
#9 {main}
  thrown in /srv/www/vhosts/my_site/wp-content/plugins/wp2static/src/DetectPluginAssets.php on line 42

Line 42 in src/DetectPluginAssets.php was doing array_keys( $active_sitewide_plugins ). A little earlier, line 36 was this:

$active_sitewide_plugins = get_option( 'active_sitewide_plugins' );

...which when I tested it returned false. Changing line 36 to

$active_sitewide_plugins = get_site_option( 'active_sitewide_plugins' );

solved the problem. ('active_sitewide_plugins' is a network option, it appears.)

My recommended fix modifies lines 33-45 or so:

 33             
 34             if ( is_multisite() ) {
 35                 /**
 36                  * @var string[] $active_sitewide_plugins
 37                  */
 38                 $active_sitewide_plugins = get_site_option( 'active_sitewide_plugins', array() );
 39                 $active_plugins = array_unique(
 40                     array_merge(
 41                         $active_plugins,
 42                         array_keys( $active_sitewide_plugins )
 43                     )
 44                 );
 45             }

Without the line numbers:

if ( is_multisite() ) { 
    /** 
     * @var string[] $active_sitewide_plugins
     */  
    $active_sitewide_plugins = get_site_option( 'active_sitewide_plugins', array() );
    $active_plugins = array_unique(
        array_merge(
            $active_plugins,
            array_keys( $active_sitewide_plugins )
        )
    );  
} 

If needed I can make this into a pull request.