[wp-trac] [WordPress Trac] #51947: When Customizer `setup_theme` action fails during wp-settings.php, WordPress crashes due to missing global $wp_locale

[WordPress Trac]

#51947: When Customizer `setup_theme` action fails during wp-settings.php,
WordPress crashes due to missing global $wp_locale
--------------------------+-----------------------------
 Reporter:  Guss77        |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Customize     |    Version:  5.5.3
 Severity:  major         |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 The `wp-settings.php` sets up the global `$wp_locale` (line 499 in
 WordPress 5.5.3) but before doing that it calls `do_action( 'setup_theme'
 );` (line 478).

 The problem is that `WP_Customize_Manager::setup_theme()` has several
 failure actions that call the class's `wp_die()` "wrapper" which -
 depending on the value of the `messenger_channel` might try to call
 `wp_enqueue_scripts()`, which will eventually call
 `wp_localize_jquery_ui_datepicker()` that expects `$wp_locale` to be
 already set. The result is a crash.

 Here is one such stack trace:

 {{{
 PHP Fatal error:  Uncaught Error: Call to a member function is_rtl() on
 null in /var/www/html/wp-includes/script-loader.php:1684
 Stack trace:
 #0 /var/www/html/wp-includes/class-wp-hook.php(287):
 wp_localize_jquery_ui_datepicker('')
 #1 /var/www/html/wp-includes/class-wp-hook.php(311):
 WP_Hook->apply_filters(NULL, Array)
 #2 /var/www/html/wp-includes/plugin.php(478): WP_Hook->do_action(Array)
 #3 /var/www/html/wp-includes/script-loader.php(2001):
 do_action('wp_enqueue_scri...')
 #4 /var/www/html/wp-includes/class-wp-customize-manager.php(454):
 wp_enqueue_scripts()
 #5 /var/www/html/wp-includes/class-wp-customize-manager.php(551):
 WP_Customize_Manager->wp_die(0, 'Non-existent ch...')
 #6 /var/www/html/wp-includes/class-wp-hook.php(287):
 WP_Customize_Manager->setup_theme('')
 #7 /var/www/html/wp-includes/class-wp-hook.php(311):
 WP_Hook->apply_filters(NULL, Array)
 #8 /var/www/html/wp-includes/plugin.php(478): WP_Hook->do_action(Array)
 #9 /var/www/html/wp-settings.php(478): do_action('setup_theme')
 #10 /var/www/html/wp-config.php(97): req...
 in /var/www/html/wp-includes/script-loader.php on line 1684, referer:
 https://somesite.com/
 }}}

 Moving the `do_action( 'setup_theme' );` line down a few lines until after
 the local has been setup, and just before loading the active theme's
 `function.php` file (which is arguably where it was supposed to be in the
 first place) solves the problem.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/51947>
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